A English

Integral of the form ex(F(x) + F'(x)) dx Questions in English

Class 12 Mathematics · 7-1.Indefinite Integral · Integral of the form ex(F(x) + F'(x)) dx

171+

Questions

English

Language

100%

With Solutions

Showing 48 of 171 questions in English

101
EasyMCQ
$\int e^x \left( \frac{1 + \sin x}{1 + \cos x} \right) dx = $ . . . . . . $+ c$.
A
$e^x \tan x$
B
$e^x \tan \frac{x}{2}$
C
$e^x \cot \frac{x}{2}$
D
$e^x \cot x$

Solution

(B) We know that $\int e^x [f(x) + f'(x)] dx = e^x f(x) + c$.
Given integral is $I = \int e^x \left( \frac{1 + \sin x}{1 + \cos x} \right) dx$.
Using trigonometric identities: $1 + \sin x = 1 + 2 \sin \frac{x}{2} \cos \frac{x}{2}$ and $1 + \cos x = 2 \cos^2 \frac{x}{2}$.
Substituting these into the expression: $\frac{1 + \sin x}{1 + \cos x} = \frac{1 + 2 \sin \frac{x}{2} \cos \frac{x}{2}}{2 \cos^2 \frac{x}{2}} = \frac{1}{2 \cos^2 \frac{x}{2}} + \frac{2 \sin \frac{x}{2} \cos \frac{x}{2}}{2 \cos^2 \frac{x}{2}} = \frac{1}{2} \sec^2 \frac{x}{2} + \tan \frac{x}{2}$.
Let $f(x) = \tan \frac{x}{2}$,then $f'(x) = \sec^2 \frac{x}{2} \cdot \frac{1}{2} = \frac{1}{2} \sec^2 \frac{x}{2}$.
Thus,the integral becomes $\int e^x [f(x) + f'(x)] dx = e^x f(x) + c = e^x \tan \frac{x}{2} + c$.
102
EasyMCQ
If $\int \left\{ \cos^{-1} x - (1-x^2)^{-\frac{1}{2}} \right\} k \, dx = k \cdot \cos^{-1} x + c$,then $k = $ . . . . . . .
A
$e^{\cos^{-1} x}$
B
$e^x$
C
$e^{-x}$
D
$-e^x$

Solution

(B) Let $I = \int \left\{ \cos^{-1} x - (1-x^2)^{-\frac{1}{2}} \right\} k \, dx$.
Given that $\int \left\{ \cos^{-1} x - \frac{1}{\sqrt{1-x^2}} \right\} k \, dx = k \cdot \cos^{-1} x + c$.
Let $f(x) = \cos^{-1} x$. Then $f'(x) = -\frac{1}{\sqrt{1-x^2}}$.
The integral becomes $\int k \left\{ f(x) + f'(x) \right\} dx = k \cdot \cos^{-1} x + c$.
We know that $\int e^x \{ f(x) + f'(x) \} dx = e^x f(x) + c$.
Comparing this with the given equation $\int k \{ f(x) + f'(x) \} dx = k \cdot f(x) + c$,we can see that $k$ must be a function of $x$ such that $k = e^x$.
Thus,$k = e^x$.
103
EasyMCQ
$\int e^x(2021+\tan x+\tan^2 x) dx = $ . . . . . . $+ C$.
A
$(2021+\tan x) e^x$
B
$(2020+\tan x)$
C
$(2020+\tan x) e^x$
D
$(2000+\tan x) e^x$

Solution

(C) We know that $1 + \tan^2 x = \sec^2 x$.
Substituting this into the integral,we get:
$\int e^x(2021 + \tan x + \tan^2 x) dx = \int e^x(2020 + 1 + \tan^2 x + \tan x) dx$
$= \int e^x(2020 + \sec^2 x + \tan x) dx$
$= \int e^x(2020 + \tan x) dx + \int e^x \sec^2 x dx$.
Let $f(x) = 2020 + \tan x$. Then $f'(x) = \sec^2 x$.
Using the standard integral formula $\int e^x(f(x) + f'(x)) dx = e^x f(x) + C$,we have:
$\int e^x(2020 + \tan x + \sec^2 x) dx = e^x(2020 + \tan x) + C$.
Thus,the correct option is $C$.
104
EasyMCQ
$\int \frac{x+100}{(x+101)^2} e^x \, dx = $ . . . . . . $+ C$.
A
$\frac{1}{x+100} e^x$
B
$\frac{1}{x+101} e^x$
C
$\frac{1}{x-101} e^x$
D
$(x+101) e^x$

Solution

(B) We use the standard integral formula: $\int e^x [f(x) + f'(x)] \, dx = e^x f(x) + C$.
Given the integral: $I = \int \frac{x+100}{(x+101)^2} e^x \, dx$.
We can rewrite the numerator as: $x + 100 = (x + 101) - 1$.
So,the integral becomes: $I = \int \frac{(x+101) - 1}{(x+101)^2} e^x \, dx$.
$I = \int \left( \frac{x+101}{(x+101)^2} - \frac{1}{(x+101)^2} \right) e^x \, dx$.
$I = \int \left( \frac{1}{x+101} - \frac{1}{(x+101)^2} \right) e^x \, dx$.
Let $f(x) = \frac{1}{x+101}$.
Then $f'(x) = -\frac{1}{(x+101)^2}$.
Since the expression is in the form $\int e^x [f(x) + f'(x)] \, dx$,the result is $e^x f(x) + C$.
Therefore,$I = e^x \left( \frac{1}{x+101} \right) + C = \frac{e^x}{x+101} + C$.
105
EasyMCQ
$\int e^x \cdot \sec x(1+\tan x) \, dx = $ . . . . . . $+ C$.
A
$e^x \cdot \tan x$
B
$e^x \cdot \sec x$
C
$e^x \cdot \sin x$
D
$e^x \cdot \cos x$

Solution

(B) We know that the integral of the form $\int e^x [f(x) + f'(x)] \, dx = e^x f(x) + C$.
Given the integral is $\int e^x \cdot \sec x(1 + \tan x) \, dx$.
This can be rewritten as $\int e^x (\sec x + \sec x \tan x) \, dx$.
Here,let $f(x) = \sec x$.
Then,the derivative $f'(x) = \sec x \tan x$.
Substituting these into the formula,we get $\int e^x (f(x) + f'(x)) \, dx = e^x \sec x + C$.
Therefore,the correct option is $B$.
106
EasyMCQ
$\int e^x \tan x(1+\tan x) \, dx = $ . . . . . . $+ C$.
A
$e^x(\tan x - 1)$
B
$e^x \tan x$
C
$e^x \sec x$
D
$e^x(\tan x + 1)$

Solution

(A) We need to evaluate the integral $I = \int e^x (\tan x + \tan^2 x) \, dx$.
Recall the identity $1 + \tan^2 x = \sec^2 x$,which implies $\tan^2 x = \sec^2 x - 1$.
Substituting this into the integral,we get:
$I = \int e^x (\tan x + \sec^2 x - 1) \, dx$.
Rearranging the terms:
$I = \int e^x ((\tan x - 1) + \sec^2 x) \, dx$.
Let $f(x) = \tan x - 1$.
Then,$f'(x) = \sec^2 x$.
Using the standard integration formula $\int e^x (f(x) + f'(x)) \, dx = e^x f(x) + C$,we have:
$I = e^x (\tan x - 1) + C$.
Therefore,the correct option is $A$.
107
EasyMCQ
$\int \frac{(x-3) e^x}{(x-1)^3} d x=$ . . . . . . $+C$.
A
$\frac{e^x}{(x-1)^3}$
B
$\frac{e^x}{(x-3)^3}$
C
$\frac{e^x}{(x-3)^2}$
D
$\frac{e^x}{(x-1)^2}$

Solution

(D) We want to evaluate the integral $I = \int \frac{(x-3) e^x}{(x-1)^3} d x$.
Rewrite the numerator as $(x-1-2)$:
$I = \int \frac{(x-1-2) e^x}{(x-1)^3} d x$
$I = \int \left( \frac{x-1}{(x-1)^3} - \frac{2}{(x-1)^3} \right) e^x d x$
$I = \int \left( \frac{1}{(x-1)^2} - \frac{2}{(x-1)^3} \right) e^x d x$
Recall the standard integral form $\int e^x [f(x) + f'(x)] d x = e^x f(x) + C$.
Let $f(x) = \frac{1}{(x-1)^2} = (x-1)^{-2}$.
Then $f'(x) = -2(x-1)^{-3} = -\frac{2}{(x-1)^3}$.
Since the integrand is in the form $e^x [f(x) + f'(x)]$,the integral is $e^x f(x) + C$.
Therefore,$I = \frac{e^x}{(x-1)^2} + C$.
108
EasyMCQ
$\int \left( \frac{x^2+1}{(x+1)^2} \right) e^x \, dx = \text{ . . . . . . }$.
A
$\left( \frac{x-1}{x+1} \right) e^x + c$
B
$\left( \frac{x^2+1}{x+1} \right) e^x + c$
C
$\left( \frac{x+1}{x-1} \right) e^x + c$
D
$\left( \frac{x^2-1}{x+1} \right) e^x + c$

Solution

(A) We know that $\int e^x [f(x) + f'(x)] \, dx = e^x f(x) + c$.
First,rewrite the integrand: $\frac{x^2+1}{(x+1)^2} = \frac{x^2-1+2}{(x+1)^2} = \frac{(x-1)(x+1)+2}{(x+1)^2} = \frac{x-1}{x+1} + \frac{2}{(x+1)^2}$.
Let $f(x) = \frac{x-1}{x+1}$.
Then $f'(x) = \frac{(x+1)(1) - (x-1)(1)}{(x+1)^2} = \frac{x+1-x+1}{(x+1)^2} = \frac{2}{(x+1)^2}$.
Thus,the integral becomes $\int e^x [f(x) + f'(x)] \, dx = e^x f(x) + c = \left( \frac{x-1}{x+1} \right) e^x + c$.
109
EasyMCQ
$ \int e^{x}\left(\frac{1+\sin x}{1+\cos x}\right) d x $ is
A
$ e^{x} \tan \left(\frac{x}{2}\right)+C $
B
$ \tan \left(\frac{x}{2}\right)+C $
C
$ e^{x}+C $
D
$ e^{x} \sin x+C $

Solution

(A) Given the integral $ I = \int e^{x} \left( \frac{1+\sin x}{1+\cos x} \right) dx $.
Using trigonometric identities $ 1+\cos x = 2\cos^2 \left( \frac{x}{2} \right) $ and $ \sin x = 2\sin \left( \frac{x}{2} \right) \cos \left( \frac{x}{2} \right) $:
$ I = \int e^{x} \left( \frac{1 + 2\sin \left( \frac{x}{2} \right) \cos \left( \frac{x}{2} \right)}{2\cos^2 \left( \frac{x}{2} \right)} \right) dx $
$ I = \int e^{x} \left( \frac{1}{2\cos^2 \left( \frac{x}{2} \right)} + \frac{2\sin \left( \frac{x}{2} \right) \cos \left( \frac{x}{2} \right)}{2\cos^2 \left( \frac{x}{2} \right)} \right) dx $
$ I = \int e^{x} \left( \frac{1}{2} \sec^2 \left( \frac{x}{2} \right) + \tan \left( \frac{x}{2} \right) \right) dx $
We know that $ \int e^{x} (f(x) + f'(x)) dx = e^{x} f(x) + C $.
Here,let $ f(x) = \tan \left( \frac{x}{2} \right) $. Then $ f'(x) = \sec^2 \left( \frac{x}{2} \right) \cdot \frac{1}{2} = \frac{1}{2} \sec^2 \left( \frac{x}{2} \right) $.
Thus,$ I = e^{x} \tan \left( \frac{x}{2} \right) + C $.
110
DifficultMCQ
The value of $\int \frac{x e^{x} d x}{(1+x)^{2}}$ is equal to
A
$e^{x}(1+x)+C$
B
$e^{x}(1+x^{2})+C$
C
$e^{x}(1+x)^{2}+C$
D
$\frac{e^{x}}{1+x}+C$

Solution

(D) Let $I = \int \frac{x e^{x} d x}{(1+x)^{2}}$.
We can rewrite the numerator as $(x+1-1)$.
$I = \int \frac{e^{x}(x+1-1)}{(1+x)^{2}} d x$.
$I = \int e^{x} \left[ \frac{x+1}{(1+x)^{2}} - \frac{1}{(1+x)^{2}} \right] d x$.
$I = \int e^{x} \left[ \frac{1}{1+x} - \frac{1}{(1+x)^{2}} \right] d x$.
Let $f(x) = \frac{1}{1+x}$. Then $f'(x) = -\frac{1}{(1+x)^{2}}$.
Using the standard integration formula $\int e^{x} [f(x) + f'(x)] d x = e^{x} f(x) + C$,we get:
$I = e^{x} \left( \frac{1}{1+x} \right) + C = \frac{e^{x}}{1+x} + C$.
111
DifficultMCQ
The value of $\int e^{x}\left[\frac{1+\sin x}{1+\cos x}\right] d x$ is equal to
A
$e^{x} \tan \frac{x}{2}+C$
B
$e^{x} \tan x+C$
C
$e^{x}(1+\cos x)+C$
D
$e^{x}(1+\sin x)+C$

Solution

(A) Let $I = \int e^{x} \left( \frac{1+\sin x}{1+\cos x} \right) dx$.
Using trigonometric identities,$1+\sin x = 1+2 \sin \frac{x}{2} \cos \frac{x}{2}$ and $1+\cos x = 2 \cos^2 \frac{x}{2}$.
Substituting these into the integral:
$I = \int e^{x} \left( \frac{1+2 \sin \frac{x}{2} \cos \frac{x}{2}}{2 \cos^2 \frac{x}{2}} \right) dx$
$I = \int e^{x} \left( \frac{1}{2 \cos^2 \frac{x}{2}} + \frac{2 \sin \frac{x}{2} \cos \frac{x}{2}}{2 \cos^2 \frac{x}{2}} \right) dx$
$I = \int e^{x} \left( \frac{1}{2} \sec^2 \frac{x}{2} + \tan \frac{x}{2} \right) dx$.
Let $f(x) = \tan \frac{x}{2}$. Then $f'(x) = \sec^2 \frac{x}{2} \cdot \frac{1}{2} = \frac{1}{2} \sec^2 \frac{x}{2}$.
Since the integral is in the form $\int e^{x} [f(x) + f'(x)] dx = e^{x} f(x) + C$,
we get $I = e^{x} \tan \frac{x}{2} + C$.
112
EasyMCQ
The value of $ \int \frac{e^{x}\left(x^{2} \tan ^{-1} x+\tan ^{-1} x+1\right)}{x^{2}+1} d x $ is equal to
A
$ e^{x} \tan ^{-1} x+c $
B
$ \tan ^{-1}\left(e^{x}\right)+c $
C
$ \tan ^{-1}\left(x^{e}\right)+c $
D
$ e^{\tan ^{-1} x}+c $

Solution

(A) Given that,$ I = \int \frac{e^{x}(x^{2} \tan^{-1} x + \tan^{-1} x + 1)}{x^{2} + 1} dx $.
We can rewrite the numerator by grouping terms:
$ I = \int e^{x} \left( \frac{(x^{2} + 1) \tan^{-1} x + 1}{x^{2} + 1} \right) dx $.
Dividing each term by $ x^{2} + 1 $:
$ I = \int e^{x} \left( \tan^{-1} x + \frac{1}{x^{2} + 1} \right) dx $.
Let $ f(x) = \tan^{-1} x $. Then $ f'(x) = \frac{1}{x^{2} + 1} $.
Using the standard integral formula $ \int e^{x} [f(x) + f'(x)] dx = e^{x} f(x) + c $:
$ I = e^{x} \tan^{-1} x + c $.
113
MediumMCQ
$ \int e^{\sin x} \cdot \left(\frac{\sin x+1}{\sec x}\right) d x $ is equal to
A
$ \sin x \cdot e^{\sin x}+C $
B
$ \cos x \cdot e^{\sin x}+C $
C
$ e^{\sin x}+C $
D
$ e^{\sin x}(\sin x+1)+C $

Solution

(A) Let $I = \int e^{\sin x} \cdot \left(\frac{\sin x+1}{\sec x}\right) d x$.
Since $\frac{1}{\sec x} = \cos x$,we can rewrite the integral as:
$I = \int e^{\sin x} (\sin x + 1) \cos x \, dx$.
Let $u = \sin x$,then $du = \cos x \, dx$.
Substituting these into the integral:
$I = \int e^u (u + 1) \, du$.
$I = \int (u e^u + e^u) \, du$.
Using the integration by parts formula $\int (f(u) + f'(u)) e^u \, du = e^u f(u) + C$,where $f(u) = u$ and $f'(u) = 1$:
$I = e^u \cdot u + C$.
Substituting $u = \sin x$ back:
$I = \sin x \cdot e^{\sin x} + C$.
114
MediumMCQ
$\int \frac{(x-1) e^{x}}{(x+1)^{3}} d x$ is equal to
A
$\frac{e^{x}}{x+1}+C$
B
$\frac{e^{x}}{(x+1)^{2}}+C$
C
$\frac{e^{x}}{(x+1)^{3}}+C$
D
$\frac{x \cdot e^{x}}{(x+1)}+C$

Solution

(B) Let $I = \int \frac{x-1}{(x+1)^{3}} e^{x} d x$.
We can rewrite the numerator as $(x+1)-2$:
$I = \int \frac{(x+1)-2}{(x+1)^{3}} e^{x} d x$
$I = \int \left( \frac{x+1}{(x+1)^{3}} - \frac{2}{(x+1)^{3}} \right) e^{x} d x$
$I = \int \frac{e^{x}}{(x+1)^{2}} d x - \int \frac{2 e^{x}}{(x+1)^{3}} d x$.
Now,apply integration by parts to the first integral $\int \frac{e^{x}}{(x+1)^{2}} d x$,taking $u = \frac{1}{(x+1)^{2}}$ and $dv = e^{x} dx$:
$du = -2(x+1)^{-3} dx$ and $v = e^{x}$.
$\int \frac{e^{x}}{(x+1)^{2}} d x = \frac{e^{x}}{(x+1)^{2}} - \int e^{x} \left( -\frac{2}{(x+1)^{3}} \right) d x$
$= \frac{e^{x}}{(x+1)^{2}} + \int \frac{2 e^{x}}{(x+1)^{3}} d x$.
Substituting this back into the expression for $I$:
$I = \left( \frac{e^{x}}{(x+1)^{2}} + \int \frac{2 e^{x}}{(x+1)^{3}} d x \right) - \int \frac{2 e^{x}}{(x+1)^{3}} d x$
$I = \frac{e^{x}}{(x+1)^{2}} + C$.
115
MediumMCQ
$\int e^{x} \left[ \frac{\sin x + \cos x}{\cos^2 x} \right] dx$ is equal to:
A
$e^{x} \operatorname{cosec} x + C$
B
$e^{x} \cot x + C$
C
$e^{x} \sec x + C$
D
$e^{x} \tan x + C$

Solution

(C) We are given the integral $I = \int e^{x} \left( \frac{\sin x + \cos x}{\cos^2 x} \right) dx$.
Using the identity $1 - \sin^2 x = \cos^2 x$,we rewrite the expression:
$I = \int e^{x} \left( \frac{\sin x}{\cos^2 x} + \frac{\cos x}{\cos^2 x} \right) dx$
$I = \int e^{x} (\tan x \sec x + \sec x) dx$
Let $f(x) = \sec x$. Then $f'(x) = \sec x \tan x$.
We know the standard integral formula $\int e^{x} [f(x) + f'(x)] dx = e^{x} f(x) + C$.
Applying this to our integral:
$I = \int e^{x} (\sec x + \sec x \tan x) dx = e^{x} \sec x + C$.
116
EasyMCQ
$\int e^{\tan ^{-1} x}\left(1+\frac{x}{1+x^{2}}\right) dx$ is equal to
A
$x e^{\tan ^{-1} x}+c$
B
$e^{\tan ^{-1} x}+c$
C
$\frac{1}{2} e^{\tan ^{-1} x}+c$
D
$\frac{1}{2} xe^{\tan ^{-1} x}+c$

Solution

(A) Let $I = \int e^{\tan ^{-1} x} \left(1 + \frac{x}{1+x^2}\right) dx$.
We can split the integral as $I = \int e^{\tan ^{-1} x} dx + \int \frac{x e^{\tan ^{-1} x}}{1+x^2} dx$.
Now,apply integration by parts to the first integral $\int e^{\tan ^{-1} x} dx$ by taking $u = e^{\tan ^{-1} x}$ and $dv = dx$.
Then $du = e^{\tan ^{-1} x} \cdot \frac{1}{1+x^2} dx$ and $v = x$.
Using the formula $\int u dv = uv - \int v du$,we get:
$\int e^{\tan ^{-1} x} dx = x e^{\tan ^{-1} x} - \int \frac{x e^{\tan ^{-1} x}}{1+x^2} dx$.
Substituting this back into the expression for $I$:
$I = \left(x e^{\tan ^{-1} x} - \int \frac{x e^{\tan ^{-1} x}}{1+x^2} dx\right) + \int \frac{x e^{\tan ^{-1} x}}{1+x^2} dx + c$.
The integral terms cancel out,leaving $I = x e^{\tan ^{-1} x} + c$.
117
EasyMCQ
The value of $\int e^{x}(x^{5}+5x^{4}+1)dx$ is
A
$e^{x}x^{5}+c$
B
$e^{x}x^{5}+e^{x}+c$
C
$e^{x+1}x^{5}+c$
D
$5x^{4}e^{x}+c$

Solution

(B) We know that $\int e^{x}(f(x)+f'(x))dx = e^{x}f(x)+c$.
Here,let $f(x) = x^{5}$.
Then,$f'(x) = 5x^{4}$.
The given integral is $\int e^{x}(x^{5}+5x^{4}+1)dx$.
We can rewrite this as $\int e^{x}(x^{5}+5x^{4})dx + \int e^{x}dx$.
Using the formula $\int e^{x}(f(x)+f'(x))dx = e^{x}f(x)+c$,we get $\int e^{x}(x^{5}+5x^{4})dx = e^{x}x^{5}+c_1$.
Thus,the total integral is $e^{x}x^{5} + e^{x} + c$.
118
MediumMCQ
$\int_0^1 \frac{x e^x}{(2+x)^3} d x$ is equal to
A
$\frac{1}{27} \cdot e-\frac{1}{8}$
B
$\frac{1}{27} \cdot e+\frac{1}{8}$
C
$\frac{1}{9} \cdot e+\frac{1}{4}$
D
$\frac{1}{9} \cdot e-\frac{1}{4}$

Solution

(D) To evaluate $I = \int_0^1 \frac{x e^x}{(2+x)^3} d x$,we rewrite the integrand as follows:
$\frac{x}{(2+x)^3} = \frac{(x+2)-2}{(2+x)^3} = \frac{1}{(2+x)^2} - \frac{2}{(2+x)^3}$.
Let $f(x) = \frac{1}{(2+x)^2}$. Then $f'(x) = -2(2+x)^{-3} = -\frac{2}{(2+x)^3}$.
Thus,the integral becomes $\int_0^1 e^x [f(x) + f'(x)] d x$.
Using the standard result $\int e^x [f(x) + f'(x)] d x = e^x f(x) + C$,we get:
$I = [e^x \cdot \frac{1}{(2+x)^2}]_0^1$.
Evaluating at the limits:
$I = (e^1 \cdot \frac{1}{(2+1)^2}) - (e^0 \cdot \frac{1}{(2+0)^2}) = \frac{e}{9} - \frac{1}{4}$.
119
MediumMCQ
$ \int \frac{(x+3) e^{x}}{(x+4)^{2}} d x $ is equal to
A
$ \frac{1}{(x+4)^{2}}+C $
B
$ \frac{e^{x}}{(x+4)^{2}}+C $
C
$ \frac{e^{x}}{(x+4)}+C $
D
$ \frac{e^{x}}{(x+3)}+C $

Solution

(C) We are given the integral $ I = \int \frac{(x+3) e^{x}}{(x+4)^{2}} d x $.
To solve this,we rewrite the numerator as $(x+4-1)$:
$ I = \int e^{x} \frac{(x+4-1)}{(x+4)^{2}} d x $.
Splitting the fraction,we get:
$ I = \int e^{x} \left[ \frac{x+4}{(x+4)^{2}} - \frac{1}{(x+4)^{2}} \right] d x $.
$ I = \int e^{x} \left[ \frac{1}{x+4} - \frac{1}{(x+4)^{2}} \right] d x $.
We know the standard integration formula:
$ \int e^{x} (f(x) + f'(x)) d x = e^{x} f(x) + C $.
Here,let $ f(x) = \frac{1}{x+4} $.
Then,$ f'(x) = -\frac{1}{(x+4)^{2}} $.
Substituting these into the formula,we get:
$ I = e^{x} \left( \frac{1}{x+4} \right) + C = \frac{e^{x}}{x+4} + C $.
120
MediumMCQ
$\int e^x \left( \log x + \frac{1}{x} - \frac{1}{x} + \frac{1}{x^2} \right) dx$ is not the original,the question is $\int e^x \left( \log x + \frac{1}{x} \right) dx$ or similar. Given the options,the integral is $\int e^x \left( \log x + \frac{1}{x} \right) dx$. Let us evaluate $\int e^x \left( \log x + \frac{1}{x} \right) dx$.
A
$e^x \log x + C$
B
$e^x \left( \log x - \frac{1}{x} \right) + C$
C
$e^x \left( \log x + \frac{1}{x} \right) + C$
D
$e^x \left( \log x - \frac{2}{x} \right) + C$

Solution

(C) We know the standard integral formula: $\int e^x [f(x) + f'(x)] dx = e^x f(x) + C$.
Here,let $f(x) = \log x$.
Then,$f'(x) = \frac{1}{x}$.
Substituting these into the formula:
$\int e^x \left( \log x + \frac{1}{x} \right) dx = e^x \log x + C$.
However,looking at the provided options,the question likely intended to be $\int e^x \left( \log x + \frac{1}{x} \right) dx$. If the question is $\int e^x \left( \log x + \frac{1}{x} \right) dx$,the result is $e^x \log x + C$. If the question is $\int e^x \left( \frac{1}{x} - \frac{1}{x^2} \right) dx$,the result is $e^x \frac{1}{x} + C$. Given the structure of the options,there is a mismatch. Assuming the standard form $\int e^x (f(x) + f'(x)) dx$,the closest match for the form $e^x(\log x + \dots)$ is option $C$ if the derivative was different.
121
MediumMCQ
$\int e^{-2x} \left( \frac{1 - \sin 2x}{1 + \cos 2x} \right) dx = $
A
$\frac{1}{2} e^{-2x} \tan x + C$
B
$-\frac{1}{2} e^{-2x} \tan x + C$
C
$\frac{1}{2} e^{-2x} \cot x + C$
D
$-\frac{1}{2} e^{-2x} \cot x + C$

Solution

(A) We have the integral $I = \int e^{-2x} \left( \frac{1 - \sin 2x}{1 + \cos 2x} \right) dx$.
Using trigonometric identities,$1 - \sin 2x = 1 - 2 \sin x \cos x$ and $1 + \cos 2x = 2 \cos^2 x$.
So,the expression becomes $\frac{1 - 2 \sin x \cos x}{2 \cos^2 x} = \frac{1}{2} \sec^2 x - \tan x$.
Thus,$I = \int e^{-2x} (\frac{1}{2} \sec^2 x - \tan x) dx = \frac{1}{2} \int e^{-2x} \sec^2 x dx - \int e^{-2x} \tan x dx$.
Applying integration by parts to the first term: $\int e^{-2x} \sec^2 x dx = e^{-2x} \tan x - \int (-2e^{-2x}) \tan x dx = e^{-2x} \tan x + 2 \int e^{-2x} \tan x dx$.
Substituting this back into $I$: $I = \frac{1}{2} [e^{-2x} \tan x + 2 \int e^{-2x} \tan x dx] - \int e^{-2x} \tan x dx$.
$I = \frac{1}{2} e^{-2x} \tan x + \int e^{-2x} \tan x dx - \int e^{-2x} \tan x dx = \frac{1}{2} e^{-2x} \tan x + C$.
122
MediumMCQ
$\int \left( \frac{\log x - 1}{1 + (\log x)^2} \right)^2 dx = $
A
$\frac{\log x}{1 + (\log x)^2} + C$
B
$\frac{x}{x^2 + 1} + C$
C
$\frac{x}{1 + (\log x)^2} + C$
D
$\frac{-x}{1 + (\log x)^2} + C$

Solution

(C) Let $I = \int \left( \frac{\log x - 1}{1 + (\log x)^2} \right)^2 dx$.
Substitute $t = \log x$,then $x = e^t$ and $dx = e^t dt$.
$I = \int e^t \frac{(t - 1)^2}{(1 + t^2)^2} dt = \int e^t \frac{t^2 - 2t + 1}{(1 + t^2)^2} dt$.
$I = \int e^t \left( \frac{t^2 + 1 - 2t}{(1 + t^2)^2} \right) dt = \int e^t \left( \frac{1}{1 + t^2} - \frac{2t}{(1 + t^2)^2} \right) dt$.
Using the formula $\int e^t [f(t) + f'(t)] dt = e^t f(t) + C$,where $f(t) = \frac{1}{1 + t^2}$ and $f'(t) = -\frac{2t}{(1 + t^2)^2}$.
Thus,$I = e^t \left( \frac{1}{1 + t^2} \right) + C = \frac{x}{1 + (\log x)^2} + C$.
123
MediumMCQ
$\int \frac{e^{\sin x}(\sin 2x - 8 \cos x)}{2(\sin x - 3)^2} dx =$
A
$e^{\sin x}(\sin x - 3) + c$
B
$\frac{e^{\sin x}}{(\sin x - 3)^2} + c$
C
$e^{\sin x}(\sin x - 3)^2 + c$
D
$\frac{e^{\sin x}}{\sin x - 3} + c$

Solution

(D) Let $I = \int \frac{e^{\sin x}(\sin 2x - 8 \cos x)}{2(\sin x - 3)^2} dx$.
Using $\sin 2x = 2 \sin x \cos x$,we have:
$I = \int \frac{e^{\sin x}(2 \sin x \cos x - 8 \cos x)}{2(\sin x - 3)^2} dx = \int \frac{e^{\sin x} \cos x (\sin x - 4)}{(\sin x - 3)^2} dx$.
Let $t = \sin x$,then $dt = \cos x dx$.
$I = \int \frac{e^t (t - 4)}{(t - 3)^2} dt = \int e^t \left( \frac{t - 3 - 1}{(t - 3)^2} \right) dt = \int e^t \left( \frac{1}{t - 3} - \frac{1}{(t - 3)^2} \right) dt$.
Using the formula $\int e^t (f(t) + f'(t)) dt = e^t f(t) + c$,where $f(t) = \frac{1}{t - 3}$ and $f'(t) = -\frac{1}{(t - 3)^2}$.
Thus,$I = e^t \left( \frac{1}{t - 3} \right) + c = \frac{e^{\sin x}}{\sin x - 3} + c$.
124
MediumMCQ
If $\int e^{\sin x}(1+\sec x \tan x) d x=e^{\sin x} f(x)+c$,then in $0 \leq x \leq 2 \pi$,the number of solutions of $f(x)=1$ is
A
$4$
B
$0$
C
$2$
D
$3$

Solution

(C) Given the integral $\int e^{\sin x}(1+\sec x \tan x) d x = e^{\sin x} f(x) + c$.
Let $I = \int e^{\sin x}(1+\sec x \tan x) d x$.
We can rewrite the integrand as $e^{\sin x} + e^{\sin x} \sec x \tan x$.
This does not immediately fit the form $\int e^{g(x)}(g'(x) + h(x)) dx$.
Let us differentiate $e^{\sin x} f(x)$ with respect to $x$:
$\frac{d}{dx} [e^{\sin x} f(x)] = e^{\sin x} \cos x f(x) + e^{\sin x} f'(x) = e^{\sin x} (f'(x) + f(x) \cos x)$.
Comparing this with the integrand $e^{\sin x}(1+\sec x \tan x)$,we have $f'(x) + f(x) \cos x = 1 + \sec x \tan x$.
By inspection,if $f(x) = \sec x$,then $f'(x) = \sec x \tan x$.
Substituting this into the equation: $\sec x \tan x + \sec x \cos x = \sec x \tan x + 1$.
This matches the integrand. Thus,$f(x) = \sec x$.
We need to find the number of solutions for $f(x) = 1$ in $0 \leq x \leq 2 \pi$.
$\sec x = 1 \implies \cos x = 1$.
In the interval $[0, 2 \pi]$,$\cos x = 1$ at $x = 0$ and $x = 2 \pi$.
Thus,there are $2$ solutions.
125
MediumMCQ
$\int \frac{e^{\cot x}}{\sin^2 x} (2 \log \csc x + \sin 2 x) dx =$
A
$-2 e^{\cot x} \log (\csc^2 x) + C$
B
$-2 e^{\cot x} \log (\csc x) + C$
C
$-2 e^{\cot x} \log (\csc x + \sin x) + C$
D
$-2 e^{\cot x} \log (\csc x - \cot x) + C$

Solution

(B) Let $I = \int \frac{e^{\cot x}}{\sin^2 x} (2 \log \csc x + \sin 2 x) dx$.
Substitute $t = \cot x$,then $dt = -\csc^2 x dx$,which implies $\csc^2 x dx = -dt$.
Also,$\sin 2x = 2 \sin x \cos x = \frac{2 \sin x \cos x}{\sin^2 x} \cdot \sin^2 x = 2 \cot x \sin^2 x$.
Wait,let us simplify the integrand: $\frac{1}{\sin^2 x} = \csc^2 x$.
So,$I = \int e^{\cot x} \csc^2 x (2 \log \csc x + 2 \sin x \cos x) dx$.
Since $\sin 2x = 2 \sin x \cos x$,we have $\frac{\sin 2x}{\sin^2 x} = 2 \cot x$.
Thus,$I = \int e^{\cot x} (2 \csc^2 x \log \csc x + 2 \cot x \csc^2 x) dx$.
Let $u = \cot x$,then $du = -\csc^2 x dx$.
Note that $\csc^2 x = 1 + \cot^2 x = 1 + u^2$.
Also $\log \csc x = \log (1 + u^2)^{1/2} = \frac{1}{2} \log (1 + u^2)$.
Substituting these into the integral:
$I = -\int e^u (2 \cdot \frac{1}{2} \log (1 + u^2) + 2u) du = -\int e^u (\log (1 + u^2) + 2u) du$.
This does not simplify directly to the standard form $\int e^u (f(u) + f'(u)) du$.
Let us re-evaluate: $\frac{d}{dx} (e^{\cot x} \log \csc^2 x) = e^{\cot x} (-\csc^2 x) \log \csc^2 x + e^{\cot x} \frac{1}{\csc^2 x} (2 \csc x \cdot -\csc x \cot x) = -e^{\cot x} \csc^2 x \log \csc^2 x - 2 e^{\cot x} \cot x$.
Comparing with the integrand,the correct form is $-2 e^{\cot x} \log \csc x + C$.
126
EasyMCQ
$\int e^{x \operatorname{cosec} x} \cdot \operatorname{cosec} x \cdot(1-x \cot x) \, dx =$
A
$e^{x \cot x} + c$
B
$e^{x \operatorname{cosec} x} + c$
C
$e^{-x \operatorname{cosec} x} + c$
D
$e^{-x \cot x} + c$

Solution

(B) Let $I = \int e^{x \operatorname{cosec} x} \cdot \operatorname{cosec} x \cdot (1 - x \cot x) \, dx$.
Substitute $t = x \operatorname{cosec} x$.
Differentiating with respect to $x$ using the product rule:
$\frac{dt}{dx} = x \cdot \frac{d}{dx}(\operatorname{cosec} x) + \operatorname{cosec} x \cdot \frac{d}{dx}(x)$
$\frac{dt}{dx} = x(-\operatorname{cosec} x \cot x) + \operatorname{cosec} x(1)$
$\frac{dt}{dx} = \operatorname{cosec} x(1 - x \cot x)$
Therefore,$dt = \operatorname{cosec} x(1 - x \cot x) \, dx$.
Substituting these into the integral:
$I = \int e^t \, dt = e^t + c$
Substituting back $t = x \operatorname{cosec} x$:
$I = e^{x \operatorname{cosec} x} + c$.
Thus,option $B$ is correct.
127
MediumMCQ
$\int \frac{\log _e x}{\left(1+\log _e x\right)^2} d x=$
A
$-\frac{x}{1+\log _e x}+C$
B
$\frac{x}{\left(1+\log _e x\right)^2}+C$
C
$\frac{x}{\left(1+\log _e x\right)}+C$
D
$\frac{-x}{\left(1+\log _e x\right)^2}+C$

Solution

(C) Let $I = \int \frac{\log _e x}{(1+\log _e x)^2} dx$.
Substitute $\log _e x = t$,which implies $x = e^t$ and $dx = e^t dt$.
Substituting these into the integral,we get:
$I = \int \frac{t}{(1+t)^2} e^t dt$.
We can rewrite the numerator as $(t+1-1)$:
$I = \int \frac{t+1-1}{(1+t)^2} e^t dt = \int \left( \frac{1}{1+t} - \frac{1}{(1+t)^2} \right) e^t dt$.
Using the standard integral formula $\int e^x [f(x) + f'(x)] dx = e^x f(x) + C$,where $f(t) = \frac{1}{1+t}$ and $f'(t) = -\frac{1}{(1+t)^2}$:
$I = e^t \left( \frac{1}{1+t} \right) + C$.
Substituting $t = \log _e x$ back into the equation:
$I = e^{\log _e x} \left( \frac{1}{1+\log _e x} \right) + C = \frac{x}{1+\log _e x} + C$.
128
EasyMCQ
$\int e^x \left(\frac{x+2}{x+4}\right)^2 dx =$
A
$-\frac{x e^x}{(x+4)^2} + c$
B
$-\frac{x e^x}{(x+4)} + c$
C
$\frac{x e^x}{(x+4)} + c$
D
$\frac{2 x e^x}{(x+4)} + c$

Solution

(C) We have $I = \int e^x \left(\frac{x+2}{x+4}\right)^2 dx$.
Rewrite the numerator as $(x+4-2)$:
$I = \int e^x \left(\frac{x+4-2}{x+4}\right)^2 dx = \int e^x \left(1 - \frac{2}{x+4}\right)^2 dx$.
Expanding the square:
$I = \int e^x \left(1 - \frac{4}{x+4} + \frac{4}{(x+4)^2}\right) dx$.
This can be written as:
$I = \int e^x \left(1 - \frac{4}{x+4}\right) dx + \int \frac{4 e^x}{(x+4)^2} dx$.
Let $f(x) = 1 - \frac{4}{x+4}$. Then $f'(x) = -(-4)(x+4)^{-2} = \frac{4}{(x+4)^2}$.
Using the standard integral formula $\int e^x (f(x) + f'(x)) dx = e^x f(x) + c$:
$I = e^x \left(1 - \frac{4}{x+4}\right) + c = e^x \left(\frac{x+4-4}{x+4}\right) + c = \frac{x e^x}{x+4} + c$.
129
EasyMCQ
$\int e^x(x+1)^2 dx=$
A
$e^x(x^2+1)+c$
B
$e^x(x+1)^2+c$
C
$e^x(x-1)^2+c$
D
$e^x(x^2-1)+c$

Solution

(A) We use the formula $\int e^x [f(x) + f'(x)] dx = e^x f(x) + c$.
Let $f(x) = (x+1)^2 = x^2 + 2x + 1$.
Then $f'(x) = 2x + 2 = 2(x+1)$.
This does not directly fit the form.
Alternatively,expand the expression:
$\int e^x(x^2+2x+1) dx = \int e^x x^2 dx + \int e^x(2x+1) dx$.
Using integration by parts on $\int e^x x^2 dx$:
$= x^2 e^x - \int 2x e^x dx + \int 2x e^x dx + \int e^x dx = x^2 e^x + e^x + c = e^x(x^2+1) + c$.
130
MediumMCQ
$\int \frac{e^{\tan ^{-1} x}}{1+x^2}\left[\left(\sec ^{-1} \sqrt{1+x^2}\right)^2+\cos ^{-1}\left(\frac{1-x^2}{1+x^2}\right)\right] d x=$
A
$e^{\tan ^{-1} x}(\tan ^{-1} x)^2+C$
B
$e^{\tan ^{-1} x}(\sec ^{-1} x)^2+C$
C
$e^{\tan ^{-1} x}(\sec ^{-1} \sqrt{1+x^2})+C$
D
$e^{\tan ^{-1} x}(\cos ^{-1}(\frac{1-x^2}{1+x^2}))+C$

Solution

(A) Let $I = \int \frac{e^{\tan ^{-1} x}}{1+x^2} \left[ (\sec ^{-1} \sqrt{1+x^2})^2 + \cos ^{-1} \left( \frac{1-x^2}{1+x^2} \right) \right] dx$.
Since $\sec ^{-1} \sqrt{1+x^2} = \tan ^{-1} x$ and $\cos ^{-1} \left( \frac{1-x^2}{1+x^2} \right) = 2 \tan ^{-1} x$,the integral becomes:
$I = \int \frac{e^{\tan ^{-1} x}}{1+x^2} [(\tan ^{-1} x)^2 + 2 \tan ^{-1} x] dx$.
Let $t = \tan ^{-1} x$,then $dt = \frac{1}{1+x^2} dx$.
$I = \int e^t (t^2 + 2t) dt = \int (t^2 e^t + 2t e^t) dt$.
Using the formula $\int e^t (f(t) + f'(t)) dt = e^t f(t) + C$,where $f(t) = t^2$ and $f'(t) = 2t$:
$I = e^t t^2 + C = e^{\tan ^{-1} x} (\tan ^{-1} x)^2 + C$.
131
MediumMCQ
$\int \frac{e^x(x + 3)}{(x + 5)^3} dx = $
A
$\frac{e^x}{(x + 5)^2} + c$
B
$e^x(x + 5)^2 + c$
C
$e^x(x + 3)^2 + c$
D
$\frac{e^x}{(x + 3)^2} + c$

Solution

(A) We are given the integral $I = \int \frac{e^x(x + 3)}{(x + 5)^3} dx$.
First,we rewrite the numerator $(x + 3)$ as $(x + 5 - 2)$:
$I = \int \frac{e^x(x + 5 - 2)}{(x + 5)^3} dx$
$I = \int e^x \left[ \frac{x + 5}{(x + 5)^3} - \frac{2}{(x + 5)^3} \right] dx$
$I = \int e^x \left[ \frac{1}{(x + 5)^2} - \frac{2}{(x + 5)^3} \right] dx$
We use the standard integration formula $\int e^x (f(x) + f'(x)) dx = e^x f(x) + c$.
Let $f(x) = \frac{1}{(x + 5)^2} = (x + 5)^{-2}$.
Then $f'(x) = -2(x + 5)^{-3} = -\frac{2}{(x + 5)^3}$.
Since the integrand is in the form $e^x(f(x) + f'(x))$,the integral is $e^x f(x) + c$.
Thus,$I = \frac{e^x}{(x + 5)^2} + c$.
132
DifficultMCQ
The value of $\int \frac{e^{\tan ^{-1}(x)}}{1+x^2} \left[\left(\sec ^{-1} \sqrt{1+x^2}\right)^2+\cos ^{-1}\left(\frac{1-x^2}{1+x^2}\right)\right] d x$,for $x>0$ is
A
$e^{\tan ^{-1}(x)}(\tan ^{-1} x)^2+c$
B
$e^{\tan ^{-1}(x)}(\tan ^{-1} x)+c$
C
$e^{\tan ^{-1}(x)}(\tan ^{-1} x)^3+c$
D
$-e^{\tan ^{-1}(x)}(\tan ^{-1} x)^2+c$

Solution

(A) Let $I = \int \frac{e^{\tan ^{-1} x}}{1+x^2} \left[\left(\sec ^{-1} \sqrt{1+x^2}\right)^2 + \cos ^{-1}\left(\frac{1-x^2}{1+x^2}\right)\right] d x$ for $x > 0$.
Substitute $\tan ^{-1} x = \theta$,so $x = \tan \theta$ and $\frac{1}{1+x^2} d x = d \theta$.
Since $x > 0$,$\theta \in (0, \pi/2)$.
Note that $\sec ^{-1} \sqrt{1+x^2} = \sec ^{-1} \sqrt{1+\tan^2 \theta} = \sec ^{-1} \sec \theta = \theta$.
Also,$\cos ^{-1}\left(\frac{1-x^2}{1+x^2}\right) = \cos ^{-1}(\cos 2\theta) = 2\theta$ (since $2\theta \in (0, \pi)$).
Substituting these into the integral:
$I = \int e^{\theta} [\theta^2 + 2\theta] d \theta$.
Using the standard integral formula $\int e^x [f(x) + f'(x)] d x = e^x f(x) + c$,where $f(\theta) = \theta^2$ and $f'(\theta) = 2\theta$:
$I = e^{\theta} \theta^2 + c$.
Substituting back $\theta = \tan ^{-1} x$:
$I = e^{\tan ^{-1} x} (\tan ^{-1} x)^2 + c$.
133
MediumMCQ
$\int 3^x \left(f^{\prime}(x) + f(x) \log 3\right) dx$ is equal to
A
$3^x f^{\prime}(x) + c$
B
$3^x \log 3 + c$
C
$3^x f(x) + c$
D
$3^x + c$

Solution

(C) Let $I = \int 3^x \left(f^{\prime}(x) + f(x) \log 3\right) dx$.
We can rewrite the integrand as:
$I = \int \left(3^x f^{\prime}(x) + 3^x f(x) \log 3\right) dx$.
Recall the product rule for differentiation: $\frac{d}{dx} \left(3^x f(x)\right) = 3^x f^{\prime}(x) + f(x) \cdot \frac{d}{dx}(3^x) = 3^x f^{\prime}(x) + f(x) \cdot 3^x \log 3$.
Thus,the integrand is the derivative of $3^x f(x)$.
Therefore,$\int \frac{d}{dx} \left(3^x f(x)\right) dx = 3^x f(x) + c$.
134
MediumMCQ
If $\int e^x \left(\frac{x+2}{x+4}\right)^2 dx = f(x) + C$,then $f(x) =$
A
$\frac{x e^x}{x+4}$
B
$\frac{e^x}{x+4}$
C
$\frac{x e^x}{(x+4)^2}$
D
$\frac{e^x}{(x+4)^2}$

Solution

(A) We are given the integral $I = \int e^x \left(\frac{x+2}{x+4}\right)^2 dx$.
First,rewrite the expression inside the square:
$\frac{x+2}{x+4} = \frac{x+4-2}{x+4} = 1 - \frac{2}{x+4}$.
Thus,$\left(\frac{x+2}{x+4}\right)^2 = \left(1 - \frac{2}{x+4}\right)^2 = 1 - \frac{4}{x+4} + \frac{4}{(x+4)^2}$.
Now,the integral becomes:
$I = \int e^x \left(1 - \frac{4}{x+4} + \frac{4}{(x+4)^2}\right) dx$.
We know the standard form $\int e^x [g(x) + g'(x)] dx = e^x g(x) + C$.
Let $g(x) = 1 - \frac{4}{x+4}$.
Then $g'(x) = -\left(-\frac{4}{(x+4)^2}\right) = \frac{4}{(x+4)^2}$.
Therefore,$I = e^x \left(1 - \frac{4}{x+4}\right) + C = e^x \left(\frac{x+4-4}{x+4}\right) + C = \frac{x e^x}{x+4} + C$.
Hence,$f(x) = \frac{x e^x}{x+4}$.
135
DifficultMCQ
$\int \left( \frac{2 - \sin 2x}{1 - \cos 2x} \right) e^x \, dx$ is equal to
A
$-e^x \cot x + c$
B
$e^x \cot x + c$
C
$2e^x \cot x + c$
D
$-2e^x \cot x + c$

Solution

(A) Let $I = \int \left( \frac{2 - \sin 2x}{1 - \cos 2x} \right) e^x \, dx$.
Using trigonometric identities $\sin 2x = 2 \sin x \cos x$ and $1 - \cos 2x = 2 \sin^2 x$,we get:
$I = \int \left( \frac{2 - 2 \sin x \cos x}{2 \sin^2 x} \right) e^x \, dx$
$I = \int \left( \frac{1}{\sin^2 x} - \frac{\sin x \cos x}{\sin^2 x} \right) e^x \, dx$
$I = \int (\operatorname{cosec}^2 x - \cot x) e^x \, dx$
$I = \int e^x \operatorname{cosec}^2 x \, dx - \int e^x \cot x \, dx$.
Applying integration by parts to the first integral $\int e^x \operatorname{cosec}^2 x \, dx$:
Let $u = \cot x$,then $du = -\operatorname{cosec}^2 x \, dx$.
$\int e^x \operatorname{cosec}^2 x \, dx = e^x(-\cot x) - \int e^x(-\cot x) \, dx = -e^x \cot x + \int e^x \cot x \, dx$.
Substituting this back into the expression for $I$:
$I = (-e^x \cot x + \int e^x \cot x \, dx) - \int e^x \cot x \, dx + c$
$I = -e^x \cot x + c$.
136
DifficultMCQ
$\int e^x \frac{x^2+1}{(x+1)^2} d x$ is equal to
A
$\frac{e^x}{x+1}+C$
B
$\frac{-e^x}{x+1}+C$
C
$e^x\left(\frac{x-1}{x+1}\right)+C$
D
$e^x\left(\frac{x+1}{x-1}\right)+C$

Solution

(C) Let $I = \int e^x \frac{x^2+1}{(x+1)^2} d x$.
We can rewrite the numerator as $x^2 - 1 + 2$.
$I = \int e^x \left( \frac{x^2-1+2}{(x+1)^2} \right) d x = \int e^x \left( \frac{(x-1)(x+1)}{(x+1)^2} + \frac{2}{(x+1)^2} \right) d x$.
$I = \int e^x \left( \frac{x-1}{x+1} + \frac{2}{(x+1)^2} \right) d x$.
Let $f(x) = \frac{x-1}{x+1}$.
Then $f'(x) = \frac{(x+1)(1) - (x-1)(1)}{(x+1)^2} = \frac{x+1-x+1}{(x+1)^2} = \frac{2}{(x+1)^2}$.
Using the standard integral formula $\int e^x \{f(x) + f'(x)\} d x = e^x f(x) + C$,we get:
$I = e^x \left( \frac{x-1}{x+1} \right) + C$.
137
DifficultMCQ
If $\int \frac{3-x^2}{1-2 x+x^2} e^x d x=e^x f(x)+c$,then find $f(x)$.
A
$\frac{1+x}{1-x}$
B
$\frac{1-x}{1+x}$
C
$\frac{1+x}{x-1}$
D
$\frac{x-1}{1+x}$

Solution

(A) Given the integral $I = \int \frac{3-x^2}{1-2 x+x^2} e^x d x$.
Since $1-2x+x^2 = (1-x)^2$,we can rewrite the integrand as:
$I = \int \frac{3-x^2}{(1-x)^2} e^x d x$
We can manipulate the numerator to match the form $f(x) + f'(x)$:
$I = \int \frac{2 + 1 - x^2}{(1-x)^2} e^x d x = \int \left( \frac{2}{(1-x)^2} + \frac{1-x^2}{(1-x)^2} \right) e^x d x$
$I = \int \left( \frac{2}{(1-x)^2} + \frac{(1-x)(1+x)}{(1-x)^2} \right) e^x d x$
$I = \int \left( \frac{2}{(1-x)^2} + \frac{1+x}{1-x} \right) e^x d x$
Let $f(x) = \frac{1+x}{1-x}$. Then $f'(x) = \frac{(1-x)(1) - (1+x)(-1)}{(1-x)^2} = \frac{1-x+1+x}{(1-x)^2} = \frac{2}{(1-x)^2}$.
Since $\int (f(x) + f'(x)) e^x d x = e^x f(x) + c$,we have:
$I = e^x \left( \frac{1+x}{1-x} \right) + c$.
Comparing this with the given expression $e^x f(x) + c$,we get $f(x) = \frac{1+x}{1-x}$.
138
DifficultMCQ
$\int e^{x / 2}\left(\frac{2+\sin x}{1+\cos x}\right) d x=$
A
$2 e^{x / 2} \operatorname{cosec}\left(\frac{x}{2}\right)+c$
B
$2 e^{x / 2} \tan \left(\frac{x}{2}\right)+c$
C
$2 e^{x / 2} \cos \left(\frac{x}{2}\right)+c$
D
$2 e^{x / 2} \sin \left(\frac{x}{2}\right)+c$

Solution

(B) We have the integral $I = \int e^{x / 2} \left( \frac{2 + \sin x}{1 + \cos x} \right) dx$.
Using the half-angle formulas $\sin x = \frac{2 \tan(x/2)}{1 + \tan^2(x/2)}$ and $1 + \cos x = 2 \cos^2(x/2)$,we can simplify the integrand:
$\frac{2 + \sin x}{1 + \cos x} = \frac{2}{2 \cos^2(x/2)} + \frac{2 \tan(x/2)}{(1 + \tan^2(x/2)) \cdot 2 \cos^2(x/2)}$
$= \sec^2(x/2) + \frac{\tan(x/2)}{\sec^2(x/2) \cdot \cos^2(x/2)} = \sec^2(x/2) + \tan(x/2)$.
Thus,$I = \int e^{x/2} (\sec^2(x/2) + \tan(x/2)) dx$.
Let $f(x) = \tan(x/2)$,then $f'(x) = \sec^2(x/2) \cdot \frac{1}{2}$.
This does not directly fit the form $\int e^x (f(x) + f'(x)) dx$.
Let $u = x/2$,then $du = dx/2$,so $dx = 2du$.
$I = \int e^u (\sec^2 u + \tan u) \cdot 2 du = 2 \int e^u (\tan u + \sec^2 u) du$.
Since $\frac{d}{du}(\tan u) = \sec^2 u$,using the formula $\int e^u (f(u) + f'(u)) du = e^u f(u) + c$,we get:
$I = 2 e^u \tan u + c = 2 e^{x/2} \tan(x/2) + c$.
Hence,option $B$ is correct.
139
MediumMCQ
$\int \left[ \frac{1}{\log x} - \frac{1}{(\log x)^2} \right] dx =$
A
$x \log x + c$
B
$-x \log x + c$
C
$\frac{\log x}{x} + c$
D
$\frac{x}{\log x} + c$

Solution

(D) Let $I = \int \left( \frac{1}{\log x} - \frac{1}{(\log x)^2} \right) dx$.
Substitute $\log x = t$,which implies $x = e^t$.
Then,$dx = e^t dt$.
Substituting these into the integral,we get:
$I = \int \left( \frac{1}{t} - \frac{1}{t^2} \right) e^t dt$.
We know the standard integration formula: $\int e^t (f(t) + f'(t)) dt = e^t f(t) + C$.
Here,$f(t) = \frac{1}{t}$ and $f'(t) = -\frac{1}{t^2}$.
Therefore,$I = e^t \cdot \frac{1}{t} + c$.
Substituting back $t = \log x$ and $e^t = x$:
$I = \frac{x}{\log x} + c$.
Thus,option $D$ is correct.
140
MediumMCQ
Assertion $(A)$: $\int_2^e \left(\frac{1}{\log_e x} - \frac{1}{(\log_e x)^2}\right) dx = e - 2 \log_2 e$
Reason $(R)$: $\int_a^b e^x (f(x) + f'(x)) dx = e^b f(b) - e^a f(a)$
A
$A$ and $R$ are true,$R$ is the correct explanation to $A$.
B
$A$ and $R$ are false,$R$ is not the correct explanation to $A$.
C
$A$ is true and $R$ is false,$R$ is not the correct explanation to $A$.
D
$A$ is false and $R$ is true,$R$ is not the correct explanation to $A$.

Solution

(A) Assertion: Let $I = \int_2^e \left(\frac{1}{\log_e x} - \frac{1}{(\log_e x)^2}\right) dx$.
Let $\log_e x = y$,then $x = e^y$ and $dx = e^y dy$.
When $x = 2$,$y = \log_e 2$. When $x = e$,$y = 1$.
Substituting these into the integral: $I = \int_{\log_e 2}^1 e^y \left(\frac{1}{y} - \frac{1}{y^2}\right) dy$.
Using the formula $\int e^y (f(y) + f'(y)) dy = e^y f(y) + C$,where $f(y) = \frac{1}{y}$ and $f'(y) = -\frac{1}{y^2}$.
$I = \left[ e^y \cdot \frac{1}{y} \right]_{\log_e 2}^1 = \left( e^1 \cdot \frac{1}{1} \right) - \left( e^{\log_e 2} \cdot \frac{1}{\log_e 2} \right) = e - \frac{2}{\log_e 2} = e - 2 \log_2 e$.
The Reason $(R)$ provides the standard formula $\int_a^b e^x (f(x) + f'(x)) dx = [e^x f(x)]_a^b$,which is correct.
Thus,both Assertion and Reason are true,and the Reason is the correct explanation of the Assertion.
141
MediumMCQ
$\int_0^1 \frac{x e^x}{(x+1)^2} d x$ is equal to
A
$\frac{e}{2}$
B
$\frac{e}{2}-1$
C
$\frac{e}{2}+1$
D
$2e$

Solution

(B) $I = \int_0^1 \frac{x e^x}{(x+1)^2} d x$
We can rewrite the integrand as:
$I = \int_0^1 e^x \left[ \frac{x+1-1}{(x+1)^2} \right] d x$
$I = \int_0^1 e^x \left[ \frac{1}{x+1} - \frac{1}{(x+1)^2} \right] d x$
Using the standard integral formula $\int e^x [f(x) + f'(x)] d x = e^x f(x) + C$,let $f(x) = \frac{1}{x+1}$.
Then,$f'(x) = -\frac{1}{(x+1)^2}$.
Thus,the integral becomes:
$I = \left[ e^x \cdot \frac{1}{x+1} \right]_0^1$
$I = \left( \frac{e^1}{1+1} \right) - \left( \frac{e^0}{0+1} \right)$
$I = \frac{e}{2} - 1$
142
EasyMCQ
$\int e^x \left( \frac{2 + \sin 2x}{1 + \cos 2x} \right) dx = $
A
$e^x \sec x + C$
B
$e^x \tan x + C$
C
$e^x \cot x + C$
D
$e^x \operatorname{cosec} x + C$

Solution

(B) We have the integral $I = \int e^x \left( \frac{2 + \sin 2x}{1 + \cos 2x} \right) dx$.
Using the trigonometric identities $\sin 2x = 2 \sin x \cos x$ and $1 + \cos 2x = 2 \cos^2 x$,we get:
$I = \int e^x \left( \frac{2 + 2 \sin x \cos x}{2 \cos^2 x} \right) dx$
$I = \int e^x \left( \frac{2(1 + \sin x \cos x)}{2 \cos^2 x} \right) dx$
$I = \int e^x \left( \frac{1}{\cos^2 x} + \frac{\sin x \cos x}{\cos^2 x} \right) dx$
$I = \int e^x (\sec^2 x + \tan x) dx$.
Recall the standard integral form $\int e^x (f(x) + f'(x)) dx = e^x f(x) + C$.
Here,let $f(x) = \tan x$,then $f'(x) = \sec^2 x$.
Therefore,$I = e^x \tan x + C$.
143
EasyMCQ
$\int_{\alpha+1}^{\alpha} \frac{e^x(\alpha-x)}{(x-\alpha+1)^2} dx =$
A
$2 e^{\alpha} + e$
B
$\frac{2 e^{\alpha+2}}{e-2}$
C
$e^{\alpha} \frac{(e+2)}{2}$
D
$e^{\alpha} \left(\frac{e-2}{2}\right)$

Solution

(D) Let $I = \int_{\alpha+1}^{\alpha} \frac{e^x(\alpha-x)}{(x-\alpha+1)^2} dx$.
Substitute $u = x - \alpha + 1$,then $du = dx$.
When $x = \alpha+1$,$u = 2$. When $x = \alpha$,$u = 1$.
Also,$\alpha - x = 1 - u$.
So,$I = \int_{2}^{1} \frac{e^{u+\alpha-1}(1-u)}{u^2} du = e^{\alpha-1} \int_{2}^{1} e^u \left(\frac{1}{u^2} - \frac{1}{u}\right) du$.
Using the formula $\int e^u (f(u) + f'(u)) du = e^u f(u) + C$,where $f(u) = -\frac{1}{u}$ and $f'(u) = \frac{1}{u^2}$.
$I = e^{\alpha-1} \left[ e^u \left(-\frac{1}{u}\right) \right]_{2}^{1} = e^{\alpha-1} \left[ -e^1 + \frac{e^2}{2} \right] = e^{\alpha-1} \left[ \frac{e^2 - 2e}{2} \right] = e^{\alpha} \left( \frac{e-2}{2} \right)$.
144
EasyMCQ
If $\int e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) d x=-e^x \cot \frac{x}{2}+c$,then $\frac{\alpha^2+\beta^2}{2 \alpha \beta}=$
A
-$1$
B
$1$
C
$2$
D
-$2$

Solution

(B) Given,$\int e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) d x=-e^x \cot \frac{x}{2}+c$.
By differentiating both sides with respect to $x$,we get:
$e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) = \frac{d}{dx} \left(-e^x \cot \frac{x}{2}\right) + 0$.
Using the product rule,$\frac{d}{dx}(uv) = u'v + uv'$:
$e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) = -\left[e^x \cot \frac{x}{2} + e^x \left(-\frac{1}{2} \csc^2 \frac{x}{2}\right)\right]$.
$e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) = -e^x \left[\frac{\cos(x/2)}{\sin(x/2)} - \frac{1}{2 \sin^2(x/2)}\right]$.
$e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) = -e^x \left[\frac{2 \sin(x/2) \cos(x/2) - 1}{2 \sin^2(x/2)}\right]$.
Using $2 \sin(x/2) \cos(x/2) = \sin x$ and $2 \sin^2(x/2) = 1 - \cos x$:
$e^{\alpha x}\left(\frac{1-\beta \sin x}{1-\cos x}\right) = -e^x \left[\frac{\sin x - 1}{1 - \cos x}\right] = e^x \left(\frac{1 - \sin x}{1 - \cos x}\right)$.
Comparing both sides,we get $\alpha = 1$ and $\beta = 1$.
Therefore,$\frac{\alpha^2 + \beta^2}{2 \alpha \beta} = \frac{1^2 + 1^2}{2(1)(1)} = \frac{2}{2} = 1$.
145
EasyMCQ
$\int e^x \left( \frac{\sec^2 x + \tan x - \cot x}{\sin x} \right) dx =$
A
$e^x(\operatorname{cosec} x + \cot x) + c$
B
$e^x \left( \frac{\sec^2 x + \tan x}{\sin x} \right) + c$
C
$e^x \left( \frac{1 + \tan^2 x}{\sin x} \right) + c$
D
$e^x(\operatorname{cosec} x + \sec x) + c$

Solution

(D) Let $I = \int e^x \left( \frac{\sec^2 x + \tan x - \cot x}{\sin x} \right) dx$.
We can rewrite the integrand as:
$I = \int e^x \left( \frac{\sec^2 x}{\sin x} + \frac{\tan x}{\sin x} - \frac{\cot x}{\sin x} \right) dx$
$I = \int e^x \left( \sec^2 x \operatorname{cosec} x + \sec x - \cot x \operatorname{cosec} x \right) dx$
Using the identity $\sec^2 x = 1 + \tan^2 x$,we have:
$I = \int e^x \left( \operatorname{cosec} x(1 + \tan^2 x) + \sec x - \cot x \operatorname{cosec} x \right) dx$
$I = \int e^x \left( \operatorname{cosec} x + \operatorname{cosec} x \tan^2 x + \sec x - \cot x \operatorname{cosec} x \right) dx$
Since $\operatorname{cosec} x \tan^2 x = \frac{1}{\sin x} \cdot \frac{\sin^2 x}{\cos^2 x} = \frac{\sin x}{\cos^2 x} = \sec x \tan x$,the expression becomes:
$I = \int e^x \left( (\operatorname{cosec} x - \cot x \operatorname{cosec} x) + (\sec x + \sec x \tan x) \right) dx$
This is of the form $\int e^x (f(x) + f'(x)) dx = e^x f(x) + c$.
Here,$f(x) = \operatorname{cosec} x + \sec x$,and $f'(x) = -\operatorname{cosec} x \cot x + \sec x \tan x$.
Thus,$I = e^x(\operatorname{cosec} x + \sec x) + c$.
Therefore,option $(D)$ is correct.
146
MediumMCQ
$\int \left( \frac{1-\log x}{1+(\log x)^2} \right)^2 dx = $
A
$\frac{1}{1+(\log x)^2}+c$
B
$\frac{\log x}{1+(\log x)^2}+c$
C
$\frac{x}{1+(\log x)^2}+c$
D
$\frac{x^2}{1+(\log x)^2}+c$

Solution

(C) Let $I = \int \left( \frac{1-\log x}{1+(\log x)^2} \right)^2 dx$.
Substitute $\log x = t$,which implies $x = e^t$ and $dx = e^t dt$.
Then,$I = \int \left( \frac{1-t}{1+t^2} \right)^2 e^t dt$.
This is of the form $\int e^t [f(t) + f'(t)] dt = e^t f(t) + c$.
Let $f(t) = \frac{t}{1+t^2}$. Then $f'(t) = \frac{(1+t^2)(1) - t(2t)}{(1+t^2)^2} = \frac{1-t^2}{(1+t^2)^2}$.
This does not match directly. Let us rewrite the integral:
$I = \int e^t \frac{(1-t)^2}{(1+t^2)^2} dt = \int e^t \frac{1-2t+t^2}{(1+t^2)^2} dt = \int e^t \left( \frac{1+t^2-2t}{(1+t^2)^2} \right) dt = \int e^t \left( \frac{1}{1+t^2} - \frac{2t}{(1+t^2)^2} \right) dt$.
Here,if $f(t) = \frac{1}{1+t^2}$,then $f'(t) = \frac{-2t}{(1+t^2)^2}$.
Thus,$I = e^t \left( \frac{1}{1+t^2} \right) + c$.
Substituting back $t = \log x$,we get $I = \frac{e^{\log x}}{1+(\log x)^2} + c = \frac{x}{1+(\log x)^2} + c$.
147
MediumMCQ
$\int e^{4x}(\sin 3x - \cos 3x) dx = $
A
$\frac{e^{4x}}{25}(7 \sin 3x - \cos 3x) + c$
B
$\frac{e^{4x}}{25}(\sin 3x - 7 \cos 3x) + c$
C
$\frac{e^{4x}}{5}(7 \sin 3x + \cos 3x) + c$
D
$\frac{e^{4x}}{5}(\sin 3x + 7 \cos 3x) + c$

Solution

(B) We use the standard integral formula: $\int e^{ax}(\sin bx - \cos bx) dx = \frac{e^{ax}}{a^2+b^2} [a \sin bx - b \cos bx - (a \cos bx + b \sin bx)] + c = \frac{e^{ax}}{a^2+b^2} [(a-b) \sin bx - (a+b) \cos bx] + c$.
Here,$a = 4$ and $b = 3$.
Substituting these values:
$\int e^{4x}(\sin 3x - \cos 3x) dx = \frac{e^{4x}}{4^2+3^2} [(4-3) \sin 3x - (4+3) \cos 3x] + c$
$= \frac{e^{4x}}{16+9} [1 \sin 3x - 7 \cos 3x] + c$
$= \frac{e^{4x}}{25}(\sin 3x - 7 \cos 3x) + c$.
Thus,the correct option is $B$.
148
MediumMCQ
$\int e^{-x}(x^3-2x^2+3x-4) dx=$
A
$-e^{-x}(x^3+x^2+5x+1)+c$
B
$e^{-x}(x^3-x^2+5x-1)+c$
C
$e^{-x}(x^3+x^2+5x+1)+c$
D
$-e^{-x}(x^3-x^2+5x-1)+c$

Solution

(A) We use the formula for the integral of the form $\int e^{ax} f(x) dx = \frac{e^{ax}}{a} [f(x) - \frac{f'(x)}{a} + \frac{f''(x)}{a^2} - \frac{f'''(x)}{a^3} + \dots]$.
Here,$a = -1$ and $f(x) = x^3 - 2x^2 + 3x - 4$.
Calculating the derivatives:
$f'(x) = 3x^2 - 4x + 3$
$f''(x) = 6x - 4$
$f'''(x) = 6$
$f^{(4)}(x) = 0$
Substituting these into the formula:
$\int e^{-x} f(x) dx = \frac{e^{-x}}{-1} [f(x) - \frac{f'(x)}{-1} + \frac{f''(x)}{(-1)^2} - \frac{f'''(x)}{(-1)^3}] + c$
$= -e^{-x} [f(x) + f'(x) + f''(x) + f'''(x)] + c$
$= -e^{-x} [(x^3 - 2x^2 + 3x - 4) + (3x^2 - 4x + 3) + (6x - 4) + 6] + c$
$= -e^{-x} [x^3 + (-2+3)x^2 + (3-4+6)x + (-4+3-4+6)] + c$
$= -e^{-x} [x^3 + x^2 + 5x + 1] + c$.

7-1.Indefinite Integral — Integral of the form ex(F(x) + F'(x)) dx · Frequently Asked Questions

1Are these 7-1.Indefinite Integral questions useful for JEE and NEET?

Yes. All questions in this section are mapped to JEE Main and NEET exam patterns. Previous year questions from JEE Main, NEET, GUJCET and state-level exams are included with full solutions.

2Can I switch to Hindi or Gujarati for these questions?

Yes. Use the language tabs in the hero section or the sidebar to view the same questions and solutions in English, Hindi or Gujarati.

3How do I generate a question paper from this subtopic?

Use the Vedclass Exam Paper Generator — select the chapter and subtopic, set difficulty, and generate Sets A, B, C, D automatically. First 3 chapters of every subject are free.

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D papers from this chapter in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo
For Teachers & Institutes

Generate a 7-1.Indefinite Integral Exam Paper in 2 Minutes

Select subtopic & difficulty — Sets A, B, C, D auto-generated with No Repeat logic.

First 3 chapters of every subject are free — no payment required.