A English

Simplification Questions in English

Competitive Exam Quantitative Aptitude · Number system · Simplification

413+

Questions

English

Language

100%

With Solutions

Showing 50 of 413 questions in English

201
MediumMCQ
If $\sqrt{1+\frac{x}{144}}=\frac{13}{12},$ then $x$ equals to
A
$1$
B
$13$
C
$27$
D
$25$

Solution

(D) Given the equation: $\sqrt{1+\frac{x}{144}} = \frac{13}{12}$
Square both sides of the equation to remove the square root:
$1 + \frac{x}{144} = \left(\frac{13}{12}\right)^2$
$1 + \frac{x}{144} = \frac{169}{144}$
Subtract $1$ from both sides:
$\frac{x}{144} = \frac{169}{144} - 1$
$\frac{x}{144} = \frac{169 - 144}{144}$
$\frac{x}{144} = \frac{25}{144}$
Multiplying both sides by $144$,we get:
$x = 25$
202
MediumMCQ
If $a = \sqrt{2} + 1$ and $b = \sqrt{2} - 1,$ then the value of $\frac{1}{a + 1} + \frac{1}{b + 1}$ will be
A
$0$
B
$1$
C
$2$
D
$-1$

Solution

(B) Given: $a = \sqrt{2} + 1$ and $b = \sqrt{2} - 1.$
We need to find the value of $\frac{1}{a + 1} + \frac{1}{b + 1}.$
Substitute the values of $a$ and $b$:
$\frac{1}{(\sqrt{2} + 1) + 1} + \frac{1}{(\sqrt{2} - 1) + 1} = \frac{1}{\sqrt{2} + 2} + \frac{1}{\sqrt{2}}.$
To simplify,rationalize the first term:
$\frac{1}{\sqrt{2} + 2} \times \frac{2 - \sqrt{2}}{2 - \sqrt{2}} = \frac{2 - \sqrt{2}}{4 - 2} = \frac{2 - \sqrt{2}}{2} = 1 - \frac{\sqrt{2}}{2} = 1 - \frac{1}{\sqrt{2}}.$
Now add the second term:
$(1 - \frac{1}{\sqrt{2}}) + \frac{1}{\sqrt{2}} = 1.$
Thus,the value is $1$.
203
MediumMCQ
If $x + \frac{1}{x} = \sqrt{13}$,then $\frac{3x}{x^2 - 1}$ is equal to:
A
$3\sqrt{13}$
B
$\frac{\sqrt{13}}{3}$
C
$1$
D
$\frac{3}{\sqrt{13}}$

Solution

(C) Given that $x + \frac{1}{x} = \sqrt{13}$.
Divide the numerator and denominator of the expression $\frac{3x}{x^2 - 1}$ by $x$:
$\frac{3x/x}{(x^2 - 1)/x} = \frac{3}{x - \frac{1}{x}}$.
We know that $(x - \frac{1}{x})^2 = (x + \frac{1}{x})^2 - 4$.
Substituting the given value: $(x - \frac{1}{x})^2 = (\sqrt{13})^2 - 4 = 13 - 4 = 9$.
Therefore,$x - \frac{1}{x} = \pm 3$.
Substituting this into our expression: $\frac{3}{\pm 3} = \pm 1$.
Since the options provided are limited,we consider the magnitude or the positive case,which is $1$.
204
MediumMCQ
What should come in place of the question mark $(?)$ in the following equation?
$\sqrt{575} \div ? \times 14.98^{2} = 450$
A
$15$
B
$10$
C
$7$
D
$12$

Solution

(D) Given equation: $\sqrt{575} \div x \times 14.98^{2} = 450$
Step $1$: Approximate the values. $\sqrt{575} \approx \sqrt{576} = 24$ and $14.98 \approx 15$.
Step $2$: Substitute the approximated values into the equation: $24 \div x \times 15^{2} = 450$.
Step $3$: Simplify the equation: $\frac{24}{x} \times 225 = 450$.
Step $4$: Solve for $x$: $\frac{24}{x} = \frac{450}{225}$.
Step $5$: $\frac{24}{x} = 2$.
Step $6$: $x = \frac{24}{2} = 12$.
Therefore,the value is $12$.
205
EasyMCQ
What should come in place of the question mark $(?)$ in the following equation?
$30.01^{2} - 19.98^{2} - ? = 21.81^{2}$
A
$49$
B
$50$
C
$16$
D
$39$

Solution

(C) To solve the equation $30.01^{2} - 19.98^{2} - ? = 21.81^{2}$,we can approximate the values to the nearest integers:
$30.01 \approx 30$
$19.98 \approx 20$
$21.81 \approx 22$
Substituting these values into the equation:
$30^{2} - 20^{2} - x = 22^{2}$
Calculate the squares:
$900 - 400 - x = 484$
Simplify the left side:
$500 - x = 484$
Solve for $x$:
$x = 500 - 484$
$x = 16$
206
EasyMCQ
What should come in place of the question mark $(?)$ in the following expression?
$820.15 + 2379.85 + 140.01 \times 4.99 = ?$
A
$4400$
B
$3900$
C
$3000$
D
$4000$

Solution

(B) To solve the expression $820.15 + 2379.85 + 140.01 \times 4.99$,we use the $BODMAS$ rule.
First,we round the numbers to their nearest integers for approximation:
$820.15 \approx 820$
$2379.85 \approx 2380$
$140.01 \approx 140$
$4.99 \approx 5$
Now,substitute these values into the expression:
$820 + 2380 + (140 \times 5)$
$= 3200 + 700$
$= 3900$
Therefore,the value that should come in place of the question mark is $3900$.
207
EasyMCQ
What should come in place of the question mark $(?)$ in the following equation?
$39.97 \%$ of $649.8 \div 13.05 = 45.12 - ?$
A
$40$
B
$15$
C
$25$
D
$10$

Solution

(C) To solve the equation,we approximate the values to the nearest integers:
$39.97 \% \approx 40 \% = 0.40$
$649.8 \approx 650$
$13.05 \approx 13$
$45.12 \approx 45$
Substituting these values into the equation:
$0.40 \times 650 \div 13 = 45 - ?$
$260 \div 13 = 45 - ?$
$20 = 45 - ?$
$? = 45 - 20 = 25$
Therefore,the value is $25$.
208
MediumMCQ
What should come in place of the question mark $(?)$ in the following expression?
$(674.87 + 59.98) \div 35.02 = ?$
A
$29$
B
$27$
C
$19$
D
$21$

Solution

(D) To solve the expression $(674.87 + 59.98) \div 35.02$,we use approximation to simplify the calculation.
$674.87 \approx 675$
$59.98 \approx 60$
$35.02 \approx 35$
Now,substitute these values into the expression:
$(675 + 60) \div 35$
$= 735 \div 35$
$= 21$
Therefore,the value that should come in place of the question mark is $21$.
209
MediumMCQ
What approximate value will come in place of the question mark $(?)$ in the given equation? (You are not expected to calculate the exact value)
$\frac{1810}{24.05} \times 7.95 + 11.02 \times 18.88 = ? - 306$
A
$1025$
B
$1225$
C
$1118$
D
$1255$

Solution

(C) To find the approximate value,we round the numbers to the nearest whole numbers:
$\frac{1810}{24} \times 8 + 11 \times 19 = x - 306$
First,calculate the division and multiplication:
$\frac{1810}{24} \approx 75.416$
$75.416 \times 8 \approx 603.33$
$11 \times 19 = 209$
Now,substitute these values into the equation:
$603 + 209 = x - 306$
$812 = x - 306$
Solve for $x$:
$x = 812 + 306$
$x = 1118$
210
EasyMCQ
What approximate value will come in place of the question mark $(?)$ in the given equation? (You are not expected to calculate the exact value)
$2775 \times \frac{160}{\sqrt{?}} = 5550$
A
$6400$
B
$5625$
C
$900$
D
$1600$

Solution

(A) Given equation: $2775 \times \frac{160}{\sqrt{x}} = 5550$
Rearranging the equation to solve for $\sqrt{x}$:
$\sqrt{x} = \frac{2775 \times 160}{5550}$
Since $2775 \times 2 = 5550$,we can simplify the fraction:
$\sqrt{x} = \frac{160}{2}$
$\sqrt{x} = 80$
Squaring both sides:
$x = 80^2 = 6400$
211
MediumMCQ
What approximate value will come in place of the question mark $(?)$ in the given equation? (You are not expected to calculate the exact value)
$24.98^{2} \times \frac{16.02^{2}}{(7.98 \times 15.04)} \times 38.93 = 130 \times ?^{2}$
A
$25$
B
$45$
C
$40$
D
$20$

Solution

(D) To find the approximate value,we round the numbers to the nearest integers:
$24.98 \approx 25$,$16.02 \approx 16$,$7.98 \approx 8$,$15.04 \approx 15$,$38.93 \approx 39$.
Substituting these values into the equation:
$25^{2} \times \frac{16^{2}}{8 \times 15} \times 39 = 130 \times x^{2}$
$\frac{625 \times 256}{120} \times 39 = 130 \times x^{2}$
Simplify the expression:
$\frac{625 \times 256 \times 39}{120} = 130 \times x^{2}$
$x^{2} = \frac{625 \times 256 \times 39}{120 \times 130}$
$x^{2} = \frac{625 \times 256 \times 39}{15600} = \frac{6240000}{15600} = 400$
$x = \sqrt{400} = 20$.
212
EasyMCQ
What approximate value will come in place of the question mark $(?)$ in the given question? (You are not expected to calculate the exact value)
$71.98 \%$ of $1200 + 35.06 \%$ of $270 = ? \%$ of $600$
A
$140$
B
$125$
C
$120$
D
$160$

Solution

(D) To find the approximate value,we round the percentages and numbers:
$71.98 \% \approx 72 \%$
$35.06 \% \approx 35 \%$
The equation becomes:
$72 \% \text{ of } 1200 + 35 \% \text{ of } 270 = x \% \text{ of } 600$
Calculate the values:
$72 \% \text{ of } 1200 = 0.72 \times 1200 = 864$
$35 \% \text{ of } 270 = 0.35 \times 270 = 94.5$
Summing these values:
$864 + 94.5 = 958.5$
Now,solve for $x$:
$958.5 = \frac{x}{100} \times 600$
$958.5 = 6x$
$x = \frac{958.5}{6} = 159.75$
Rounding to the nearest whole number,we get $x \approx 160$.
213
MediumMCQ
What approximate value will come in place of the question mark $(?)$ in the given equation? (You are not expected to calculate the exact value)
$\frac{7702}{43.96} + 25.11 \times 45.88 = ? \times 15$
A
$88$
B
$82$
C
$68$
D
$76$

Solution

(A) To find the approximate value,we round the numbers to the nearest whole numbers:
$\frac{7702}{44} + 25 \times 46 = x \times 15$
First,calculate the division:
$7702 \div 44 \approx 175.045 \approx 175$
Next,calculate the multiplication:
$25 \times 46 = 1150$
Now,add the results:
$175 + 1150 = 1325$
Finally,solve for $x$:
$1325 = x \times 15$
$x = \frac{1325}{15} \approx 88.33$
Rounding to the nearest integer,we get $x \approx 88$.
214
DifficultMCQ
Choose the incorrect relation$(s)$ from the following:
$(i)$ $\sqrt{6}+\sqrt{2}=\sqrt{5}+\sqrt{3}$
$(ii)$ $\sqrt{6}+\sqrt{2}<\sqrt{5}+\sqrt{3}$
$(iii)$ $\sqrt{6}+\sqrt{2}>\sqrt{5}+\sqrt{3}$
A
$(i)$
B
$(ii)$
C
$(i)$ and $(ii)$
D
$(i)$ and $(iii)$

Solution

(D) To compare the values,we use the approximate values of the square roots:
$\sqrt{2} \approx 1.414$
$\sqrt{3} \approx 1.732$
$\sqrt{5} \approx 2.236$
$\sqrt{6} \approx 2.449$
Now,calculate the sums:
$\sqrt{6} + \sqrt{2} \approx 2.449 + 1.414 = 3.863$
$\sqrt{5} + \sqrt{3} \approx 2.236 + 1.732 = 3.968$
Comparing the two sums:
$3.863 < 3.968$
Therefore,$\sqrt{6} + \sqrt{2} < \sqrt{5} + \sqrt{3}$.
This means statement $(ii)$ is correct,while statements $(i)$ and $(iii)$ are incorrect.
215
MediumMCQ
The value of $\frac{(0.67 \times 0.67 \times 0.67)-(0.33 \times 0.33 \times 0.33)}{(0.67 \times 0.67)+(0.67 \times 0.33)+(0.33 \times 0.33)}$ is:
A
$3.4$
B
$0.34$
C
$11$
D
$1.1$

Solution

(B) Let $a = 0.67$ and $b = 0.33$.
The given expression is in the form $\frac{a^3 - b^3}{a^2 + ab + b^2}$.
Using the algebraic identity $a^3 - b^3 = (a - b)(a^2 + ab + b^2)$,we can simplify the expression:
$\frac{(a - b)(a^2 + ab + b^2)}{a^2 + ab + b^2} = a - b$.
Substituting the values of $a$ and $b$ back into the simplified expression:
$a - b = 0.67 - 0.33 = 0.34$.
216
DifficultMCQ
$\frac{6^{2}+7^{2}+8^{2}+9^{2}+10^{2}}{\sqrt{7+4 \sqrt{3}}-\sqrt{4+2 \sqrt{3}}}$ is equal to
A
$355$
B
$330$
C
$366$
D
$305$

Solution

(B) First,simplify the denominator:
$\sqrt{7+4 \sqrt{3}} = \sqrt{7+2 \times 2 \times \sqrt{3}} = \sqrt{4+3+2 \times 2 \times \sqrt{3}} = \sqrt{(2+\sqrt{3})^{2}} = 2+\sqrt{3}$
$\sqrt{4+2 \sqrt{3}} = \sqrt{3+1+2 \times \sqrt{3} \times 1} = \sqrt{(\sqrt{3}+1)^{2}} = \sqrt{3}+1$
Denominator $= (2+\sqrt{3}) - (\sqrt{3}+1) = 2+\sqrt{3}-\sqrt{3}-1 = 1$
Next,calculate the numerator using the sum of squares formula $\sum_{k=1}^{n} k^{2} = \frac{n(n+1)(2n+1)}{6}$:
Sum of squares from $1$ to $10 = \frac{10(11)(21)}{6} = 385$
Sum of squares from $1$ to $5 = \frac{5(6)(11)}{6} = 55$
Numerator $= 6^{2}+7^{2}+8^{2}+9^{2}+10^{2} = 385 - 55 = 330$
Result $= \frac{330}{1} = 330$
217
MediumMCQ
If the cube root of $79507$ is $43$,then the value of $\sqrt[3]{79.507} + \sqrt[3]{0.079507} + \sqrt[3]{0.000079507}$ is
A
$47.73$
B
$0.4773$
C
$477.3$
D
$4.773$

Solution

(D) Given that $\sqrt[3]{79507} = 43$.
We need to evaluate the expression: $\sqrt[3]{79.507} + \sqrt[3]{0.079507} + \sqrt[3]{0.000079507}$.
$1$. $\sqrt[3]{79.507} = \sqrt[3]{\frac{79507}{1000}} = \frac{43}{10} = 4.3$.
$2$. $\sqrt[3]{0.079507} = \sqrt[3]{\frac{79507}{1000000}} = \frac{43}{100} = 0.43$.
$3$. $\sqrt[3]{0.000079507} = \sqrt[3]{\frac{79507}{1000000000}} = \frac{43}{1000} = 0.043$.
Adding these values together:
$4.3 + 0.43 + 0.043 = 4.773$.
218
DifficultMCQ
Find the value of $\frac{(0.064-0.008)(0.16-0.04)}{(0.16+0.08+0.04)(0.4+0.2)^{3}}$.
A
$\frac{1}{9}$
B
$3$
C
$\frac{3}{2}$
D
$\frac{2}{3}$

Solution

(A) Given expression: $\frac{(0.064-0.008)(0.16-0.04)}{(0.16+0.08+0.04)(0.4+0.2)^{3}}$
Express the terms as powers of $0.4$ and $0.2$:
$0.064 = 0.4^{3}$,$0.008 = 0.2^{3}$,$0.16 = 0.4^{2}$,$0.04 = 0.2^{2}$,$0.08 = 0.4 \times 0.2$
Substitute these into the expression:
Numerator: $(0.4^{3}-0.2^{3})(0.4^{2}-0.2^{2})$
Denominator: $(0.4^{2}+0.4 \times 0.2+0.2^{2})(0.4+0.2)^{3}$
Using algebraic identities $a^{3}-b^{3} = (a-b)(a^{2}+ab+b^{2})$ and $a^{2}-b^{2} = (a-b)(a+b)$:
Numerator: $(0.4-0.2)(0.4^{2}+0.4 \times 0.2+0.2^{2}) \times (0.4-0.2)(0.4+0.2)$
Now the expression becomes:
$\frac{(0.4-0.2)(0.4^{2}+0.4 \times 0.2+0.2^{2})(0.4-0.2)(0.4+0.2)}{(0.4^{2}+0.4 \times 0.2+0.2^{2})(0.4+0.2)^{3}}$
Cancel the common terms $(0.4^{2}+0.4 \times 0.2+0.2^{2})$ and one $(0.4+0.2)$:
$= \frac{(0.4-0.2)^{2}}{(0.4+0.2)^{2}} = \frac{(0.2)^{2}}{(0.6)^{2}} = \frac{0.04}{0.36} = \frac{4}{36} = \frac{1}{9}$
219
MediumMCQ
If $x = \sqrt{a \sqrt[3]{b \sqrt{a \sqrt[3]{b \dots \infty}}}},$ then the value of $x$ is:
A
$\sqrt[5]{a^3 b}$
B
$\sqrt[5]{a^2 b}$
C
$\sqrt[5]{a^3 b^2}$
D
$\sqrt[5]{a^2 b^3}$

Solution

(A) Given the expression $x = \sqrt{a \sqrt[3]{b \sqrt{a \sqrt[3]{b \dots \infty}}}}.$
Squaring both sides,we get $x^2 = a \sqrt[3]{b \sqrt{a \sqrt[3]{b \dots \infty}}}.$
Now,cubing both sides of this equation,we get $(x^2)^3 = a^3 \cdot b \sqrt{a \sqrt[3]{b \dots \infty}}.$
This simplifies to $x^6 = a^3 b x.$
Since $x \neq 0,$ we can divide by $x$ to get $x^5 = a^3 b.$
Therefore,$x = \sqrt[5]{a^3 b}.$
220
MediumMCQ
If $\frac{x}{y} = \frac{3}{4},$ the ratio of $(2x + 3y)$ and $(3y - 2x)$ is
A
$3:2$
B
$3:1$
C
$1:1$
D
$2:1$

Solution

(B) Given that $\frac{x}{y} = \frac{3}{4}.$ Let $x = 3k$ and $y = 4k$ for some constant $k \neq 0.$
We need to find the ratio $\frac{2x + 3y}{3y - 2x}.$
Substituting the values of $x$ and $y$:
$\frac{2(3k) + 3(4k)}{3(4k) - 2(3k)} = \frac{6k + 12k}{12k - 6k}$
$= \frac{18k}{6k} = \frac{18}{6} = \frac{3}{1}.$
Therefore,the ratio is $3:1$.
221
MediumMCQ
The value of: $\sqrt{\frac{0.324 \times 0.081 \times 4.624}{1.5625 \times 0.0289 \times 72.9 \times 64}}$
A
$0.24$
B
$0.024$
C
$2.4$
D
$24$

Solution

(B) To solve the expression,first remove the decimals by adjusting the powers of $10$ in the numerator and denominator.
$\sqrt{\frac{0.324 \times 0.081 \times 4.624}{1.5625 \times 0.0289 \times 72.9 \times 64}} = \sqrt{\frac{324 \times 10^{-3} \times 81 \times 10^{-3} \times 4624 \times 10^{-3}}{15625 \times 10^{-4} \times 289 \times 10^{-4} \times 729 \times 10^{-1} \times 64}}$
$= \sqrt{\frac{324 \times 81 \times 4624 \times 10^{-9}}{15625 \times 289 \times 729 \times 64 \times 10^{-9}}}$
$= \sqrt{\frac{324 \times 81 \times 4624}{15625 \times 289 \times 729 \times 64}}$
$= \sqrt{\frac{18^2 \times 9^2 \times 68^2}{125^2 \times 17^2 \times 27^2 \times 8^2}}$
$= \frac{18 \times 9 \times 68}{125 \times 17 \times 27 \times 8}$
$= \frac{11016}{459000} = 0.024$
222
MediumMCQ
If $\frac{x^{24}+1}{x^{12}}=7$,then find the value of $\frac{x^{72}+1}{x^{36}}$.
A
$432$
B
$433$
C
$343$
D
$322$

Solution

(D) Given: $\frac{x^{24}+1}{x^{12}}=7$
Dividing each term in the numerator by the denominator:
$\frac{x^{24}}{x^{12}}+\frac{1}{x^{12}}=7$
$x^{12}+\frac{1}{x^{12}}=7$ ..... $(1)$
We need to find the value of $\frac{x^{72}+1}{x^{36}}$,which is $x^{36}+\frac{1}{x^{36}}$.
Using the identity $(a+b)^3 = a^3+b^3+3ab(a+b)$,let $a=x^{12}$ and $b=\frac{1}{x^{12}}$:
$\left(x^{12}+\frac{1}{x^{12}}\right)^3 = (x^{12})^3 + \left(\frac{1}{x^{12}}\right)^3 + 3(x^{12})\left(\frac{1}{x^{12}}\right)\left(x^{12}+\frac{1}{x^{12}}\right)$
Substitute the value from equation $(1)$:
$7^3 = x^{36} + \frac{1}{x^{36}} + 3(1)(7)$
$343 = x^{36} + \frac{1}{x^{36}} + 21$
$x^{36} + \frac{1}{x^{36}} = 343 - 21$
$x^{36} + \frac{1}{x^{36}} = 322$
Thus,$\frac{x^{72}+1}{x^{36}} = 322$.
223
EasyMCQ
If $x=2$,then find the value of $x^{3}+27x^{2}+243x+631$.
A
$1233$
B
$1231$
C
$1321$
D
$1211$

Solution

(A) Given expression: $x^{3}+27x^{2}+243x+631$.
Substitute $x=2$ into the expression:
$= (2)^{3} + 27(2)^{2} + 243(2) + 631$
$= 8 + 27(4) + 486 + 631$
$= 8 + 108 + 486 + 631$
$= 1233$.
224
EasyMCQ
If $p = 99$,then the value of $p(p^{2} + 3p + 3)$ is:
A
$999999$
B
$988899$
C
$989898$
D
$998889$

Solution

(A) Given expression: $p(p^{2} + 3p + 3) = p^{3} + 3p^{2} + 3p$.
To simplify this,we can add and subtract $1$ to complete the cube formula: $(p+1)^{3} = p^{3} + 3p^{2} + 3p + 1$.
Therefore,$p^{3} + 3p^{2} + 3p = (p+1)^{3} - 1$.
Substitute $p = 99$ into the expression:
$(99 + 1)^{3} - 1 = 100^{3} - 1$.
$100^{3} = 1000000$.
$1000000 - 1 = 999999$.
225
MediumMCQ
If $a^{2}+b^{2}+c^{2}=ab+bc+ac,$ then the value of $\frac{a+c}{b}$ is:
A
$0$
B
$2$
C
$1$
D
$-1$

Solution

(B) Given the equation: $a^{2}+b^{2}+c^{2}=ab+bc+ca$.
Rearranging the terms,we get: $a^{2}+b^{2}+c^{2}-ab-bc-ca=0$.
Multiplying the entire equation by $2$,we get: $2a^{2}+2b^{2}+2c^{2}-2ab-2bc-2ca=0$.
This can be rewritten as: $(a^{2}-2ab+b^{2})+(b^{2}-2bc+c^{2})+(c^{2}-2ca+a^{2})=0$.
This simplifies to: $(a-b)^{2}+(b-c)^{2}+(c-a)^{2}=0$.
Since the sum of squares is zero,each term must individually be zero:
$a-b=0 \Rightarrow a=b$,
$b-c=0 \Rightarrow b=c$,
$c-a=0 \Rightarrow c=a$.
Thus,$a=b=c$.
Substituting these values into the expression $\frac{a+c}{b}$:
$\frac{a+c}{b} = \frac{a+a}{a} = \frac{2a}{a} = 2$.
226
DifficultMCQ
If $ab + bc + ca = 0$,then the value of $\left(\frac{1}{a^2 - bc} + \frac{1}{b^2 - ca} + \frac{1}{c^2 - ab}\right)$ is
A
$0$
B
$1$
C
$abc$
D
$a + b + c$

Solution

(A) Given $ab + bc + ca = 0$.
From this,we have $bc = -ab - ca$.
Substituting this into the first term denominator: $a^2 - bc = a^2 - (-ab - ca) = a^2 + ab + ca = a(a + b + c)$.
Similarly,for the other denominators:
$b^2 - ca = b^2 - (-ab - bc) = b^2 + ab + bc = b(a + b + c)$.
$c^2 - ab = c^2 - (-bc - ca) = c^2 + bc + ca = c(a + b + c)$.
Now,substitute these into the expression:
$\frac{1}{a(a + b + c)} + \frac{1}{b(a + b + c)} + \frac{1}{c(a + b + c)}$
$= \frac{1}{a + b + c} \left(\frac{1}{a} + \frac{1}{b} + \frac{1}{c}\right)$
$= \frac{1}{a + b + c} \left(\frac{bc + ac + ab}{abc}\right)$
Since $ab + bc + ca = 0$,the numerator of the second fraction is $0$.
$= \frac{1}{a + b + c} \times \frac{0}{abc} = 0$.
227
MediumMCQ
If $(2+\sqrt{3}) a=(2-\sqrt{3}) b=1,$ then the value of $\frac{1}{a}+\frac{1}{b}$ is
A
$1$
B
$2$
C
$2\sqrt{3}$
D
$4$

Solution

(D) Given that $(2+\sqrt{3}) a = 1$ and $(2-\sqrt{3}) b = 1$.
From $(2+\sqrt{3}) a = 1$,we get $a = \frac{1}{2+\sqrt{3}}$.
Therefore,$\frac{1}{a} = 2+\sqrt{3}$.
Similarly,from $(2-\sqrt{3}) b = 1$,we get $b = \frac{1}{2-\sqrt{3}}$.
Therefore,$\frac{1}{b} = 2-\sqrt{3}$.
Now,adding the two values:
$\frac{1}{a} + \frac{1}{b} = (2+\sqrt{3}) + (2-\sqrt{3}) = 4$.
228
MediumMCQ
If $3x + \frac{3}{x} = 1$,then $x^{3} + \frac{1}{x^{3}} + 1$ is
A
$0$
B
$\frac{1}{27}$
C
$\frac{5}{27}$
D
$\frac{28}{27}$

Solution

(B) Given the equation: $3x + \frac{3}{x} = 1$.
Divide the entire equation by $3$ to get: $x + \frac{1}{x} = \frac{1}{3}$.
Now,cube both sides of the equation using the identity $(a + b)^{3} = a^{3} + b^{3} + 3ab(a + b)$:
$(x + \frac{1}{x})^{3} = (\frac{1}{3})^{3}$
$x^{3} + \frac{1}{x^{3}} + 3(x)(\frac{1}{x})(x + \frac{1}{x}) = \frac{1}{27}$
Substitute the value $x + \frac{1}{x} = \frac{1}{3}$ into the equation:
$x^{3} + \frac{1}{x^{3}} + 3(1)(\frac{1}{3}) = \frac{1}{27}$
$x^{3} + \frac{1}{x^{3}} + 1 = \frac{1}{27}$.
229
DifficultMCQ
The value of $\frac{1}{a^{2}+a x+x^{2}}-\frac{1}{a^{2}-a x+x^{2}}+\frac{2 a x}{a^{4}+a^{2} x^{2}+x^{4}}$ is
A
$2$
B
$1$
C
$-1$
D
$0$

Solution

(D) Let the expression be $E = \frac{1}{a^{2}+a x+x^{2}}-\frac{1}{a^{2}-a x+x^{2}}+\frac{2 a x}{a^{4}+a^{2} x^{2}+x^{4}}$.
First,simplify the first two terms by taking the common denominator $(a^{2}+a x+x^{2})(a^{2}-a x+x^{2})$.
Note that $(a^{2}+a x+x^{2})(a^{2}-a x+x^{2}) = (a^{2}+x^{2})^{2} - (ax)^{2} = a^{4} + 2a^{2}x^{2} + x^{4} - a^{2}x^{2} = a^{4} + a^{2}x^{2} + x^{4}$.
So,the expression becomes:
$E = \frac{(a^{2}-a x+x^{2}) - (a^{2}+a x+x^{2})}{a^{4}+a^{2}x^{2}+x^{4}} + \frac{2 a x}{a^{4}+a^{2} x^{2}+x^{4}}$
$E = \frac{a^{2}-a x+x^{2}-a^{2}-a x-x^{2}}{a^{4}+a^{2}x^{2}+x^{4}} + \frac{2 a x}{a^{4}+a^{2} x^{2}+x^{4}}$
$E = \frac{-2ax}{a^{4}+a^{2}x^{2}+x^{4}} + \frac{2ax}{a^{4}+a^{2} x^{2}+x^{4}}$
$E = 0$.
230
DifficultMCQ
What is the value of $\frac{(941+149)^{2}+(941-149)^{2}}{(941 \times 941+149 \times 149)}$?
A
$10$
B
$2$
C
$1$
D
$100$

Solution

(B) Let $a = 941$ and $b = 149$.
The given expression is of the form $\frac{(a+b)^{2} + (a-b)^{2}}{a^{2} + b^{2}}$.
Expanding the numerator using algebraic identities $(a+b)^{2} = a^{2} + b^{2} + 2ab$ and $(a-b)^{2} = a^{2} + b^{2} - 2ab$:
Numerator $= (a^{2} + b^{2} + 2ab) + (a^{2} + b^{2} - 2ab) = 2(a^{2} + b^{2})$.
Substituting this back into the expression:
$\frac{2(a^{2} + b^{2})}{a^{2} + b^{2}} = 2$.
Therefore,the value of the expression is $2$.
231
EasyMCQ
If $5 \sqrt{5} \times 5^{3} \div 5^{-\frac{3}{2}} = 5^{a+2},$ then the value of $a$ is
A
$4$
B
$5$
C
$6$
D
$8$

Solution

(A) Given the expression: $5 \sqrt{5} \times 5^{3} \div 5^{-\frac{3}{2}} = 5^{a+2}$
Express all terms with base $5$:
$5^1 \times 5^{1/2} \times 5^3 \div 5^{-3/2} = 5^{a+2}$
Using the laws of exponents $x^m \times x^n = x^{m+n}$ and $x^m \div x^n = x^{m-n}$:
$5^{(1 + 1/2 + 3 - (-3/2))} = 5^{a+2}$
Simplify the exponent:
$1 + 0.5 + 3 + 1.5 = 6$
So,$5^6 = 5^{a+2}$
Equating the exponents:
$6 = a + 2$
$a = 6 - 2 = 4$
232
MediumMCQ
The value of $(3+2 \sqrt{2})^{-3}+(3-2 \sqrt{2})^{-3}$ is
A
$198$
B
$27$
C
$36$
D
$49$

Solution

(A) Let $x = 3+2 \sqrt{2}$ and $y = 3-2 \sqrt{2}$.
Note that $xy = (3+2 \sqrt{2})(3-2 \sqrt{2}) = 3^2 - (2 \sqrt{2})^2 = 9 - 8 = 1$.
We need to find $x^{-3} + y^{-3} = \frac{1}{x^3} + \frac{1}{y^3} = \frac{x^3 + y^3}{(xy)^3}$.
Since $xy = 1$,this simplifies to $x^3 + y^3$.
Using the identity $x^3 + y^3 = (x+y)^3 - 3xy(x+y)$:
$x+y = (3+2 \sqrt{2}) + (3-2 \sqrt{2}) = 6$.
$x^3 + y^3 = (6)^3 - 3(1)(6) = 216 - 18 = 198$.
233
MediumMCQ
The value of $\left\{\left(\sqrt[n]{x^{2}}\right)^{n / 2}\right\}^{2}$ is
A
$x^{2}$
B
$\frac{1}{x^{2}}$
C
$x$
D
$x^{\frac{n}{2}}$

Solution

(A) Given expression: $\left\{\left(\sqrt[n]{x^{2}}\right)^{n / 2}\right\}^{2}$
Step $1$: Simplify the inner term $\sqrt[n]{x^{2}}$. This can be written as $(x^{2})^{1/n} = x^{2/n}$.
Step $2$: Substitute this back into the expression: $\left\{(x^{2/n})^{n/2}\right\}^{2}$.
Step $3$: Use the power rule $(a^{m})^{n} = a^{m \cdot n}$. The expression becomes $\left\{x^{(2/n) \cdot (n/2)}\right\}^{2}$.
Step $4$: Simplify the exponent: $(2/n) \cdot (n/2) = 1$. So,the expression simplifies to $\{x^{1}\}^{2}$.
Step $5$: Finally,$x^{1 \cdot 2} = x^{2}$.
234
MediumMCQ
If $(\sqrt{3})^{5} \times 9^{2} = 3^{n} \times 3 \sqrt{3}$,then find the value of $n$.
A
$4$
B
$5$
C
$2$
D
$3$

Solution

(B) Given equation: $(\sqrt{3})^{5} \times 9^{2} = 3^{n} \times 3 \sqrt{3}$
Express all terms with base $3$:
$(\sqrt{3})^{5} = (3^{1/2})^{5} = 3^{5/2}$
$9^{2} = (3^{2})^{2} = 3^{4}$
$3 \sqrt{3} = 3^{1} \times 3^{1/2} = 3^{1 + 1/2} = 3^{3/2}$
Substitute these into the equation:
$3^{5/2} \times 3^{4} = 3^{n} \times 3^{3/2}$
Using the law of exponents $a^{m} \times a^{n} = a^{m+n}$:
$3^{5/2 + 4} = 3^{n + 3/2}$
$3^{13/2} = 3^{n + 3/2}$
Equating the exponents:
$13/2 = n + 3/2$
$n = 13/2 - 3/2$
$n = 10/2$
$n = 5$
235
MediumMCQ
If $p=99,$ then the value of $p(p^{2}+3p+3)$ is
A
$999999$
B
$10000001$
C
$9999999$
D
$1000001$

Solution

(A) Given expression: $p(p^{2}+3p+3)$
$= p^{3}+3p^{2}+3p$
To complete the algebraic identity $(p+1)^{3} = p^{3}+3p^{2}+3p+1$,we add and subtract $1$:
$= (p^{3}+3p^{2}+3p+1) - 1$
$= (p+1)^{3} - 1$
Substitute $p=99$:
$= (99+1)^{3} - 1$
$= 100^{3} - 1$
$= 1000000 - 1$
$= 999999$
236
MediumMCQ
Solve for $x: 3^{x}-3^{x-1}=486$
A
$5$
B
$6$
C
$7$
D
$9$

Solution

(B) Given equation: $3^{x}-3^{x-1}=486$
We can rewrite $3^{x-1}$ as $\frac{3^{x}}{3}$:
$3^{x}-\frac{3^{x}}{3}=486$
Factor out $3^{x}$:
$3^{x}(1-\frac{1}{3})=486$
Simplify the expression inside the parentheses:
$3^{x}(\frac{2}{3})=486$
Multiply both sides by $\frac{3}{2}$:
$3^{x}=486 \times \frac{3}{2}$
$3^{x}=243 \times 3$
$3^{x}=729$
Express $729$ as a power of $3$:
$729 = 3^{6}$
Therefore,$3^{x}=3^{6}$,which implies $x=6$.
237
DifficultMCQ
What is the value of $\frac{2.75 \times 2.75 \times 2.75 - 2.25 \times 2.25 \times 2.25}{2.75 \times 2.75 + 2.75 \times 2.25 + 2.25 \times 2.25}$?
A
$1$
B
$\frac{1}{2}$
C
$3$
D
$\frac{3}{2}$

Solution

(B) Let $a = 2.75$ and $b = 2.25$.
The given expression is of the form $\frac{a^3 - b^3}{a^2 + ab + b^2}$.
We know the algebraic identity: $a^3 - b^3 = (a - b)(a^2 + ab + b^2)$.
Substituting this into the expression,we get:
$\frac{(a - b)(a^2 + ab + b^2)}{a^2 + ab + b^2} = a - b$.
Now,substitute the values of $a$ and $b$ back:
$2.75 - 2.25 = 0.5$.
Since $0.5 = \frac{1}{2}$,the correct option is $B$.
238
MediumMCQ
The value of $1-\frac{a}{1-\frac{1}{1+\frac{a}{1-a}}}$ is
A
$1$
B
$0$
C
$a$
D
$1-a$

Solution

(B) To simplify the expression $1-\frac{a}{1-\frac{1}{1+\frac{a}{1-a}}}$,we start from the innermost fraction:
First,simplify the denominator $1+\frac{a}{1-a}$:
$1+\frac{a}{1-a} = \frac{1-a+a}{1-a} = \frac{1}{1-a}$
Next,substitute this back into the expression:
$1-\frac{a}{1-\frac{1}{\frac{1}{1-a}}} = 1-\frac{a}{1-(1-a)}$
Now,simplify the denominator $1-(1-a)$:
$1-1+a = a$
Finally,substitute this back:
$1-\frac{a}{a} = 1-1 = 0$
Thus,the correct option is $B$.
239
MediumMCQ
The value of $\frac{(243)^{\frac{n}{5}} \times 3^{2n+1}}{9^{n} \times 3^{n-1}}$ is
A
$6$
B
$12$
C
$3$
D
$9$

Solution

(D) Given expression: $\frac{(243)^{\frac{n}{5}} \times 3^{2n+1}}{9^{n} \times 3^{n-1}}$
Express all terms with base $3$:
$243 = 3^5$ and $9 = 3^2$.
Substitute these into the expression:
$\frac{(3^5)^{\frac{n}{5}} \times 3^{2n+1}}{(3^2)^n \times 3^{n-1}}$
Simplify the exponents:
$= \frac{3^n \times 3^{2n+1}}{3^{2n} \times 3^{n-1}}$
Combine the exponents using the rule $a^m \times a^n = a^{m+n}$:
$= \frac{3^{n + 2n + 1}}{3^{2n + n - 1}} = \frac{3^{3n+1}}{3^{3n-1}}$
Use the rule $\frac{a^m}{a^n} = a^{m-n}$:
$= 3^{(3n+1) - (3n-1)} = 3^{3n+1-3n+1} = 3^2 = 9$.
240
MediumMCQ
If $x = y = 333$ and $z = 334$,then the value of $x^{3} + y^{3} + z^{3} - 3xyz$ is
A
$0$
B
$667$
C
$1000$
D
$2334$

Solution

(C) The algebraic identity for $x^{3} + y^{3} + z^{3} - 3xyz$ is given by:
$x^{3} + y^{3} + z^{3} - 3xyz = \frac{1}{2}(x + y + z)[(x - y)^{2} + (y - z)^{2} + (z - x)^{2}]$
Given $x = 333$,$y = 333$,and $z = 334$:
Sum $(x + y + z) = 333 + 333 + 334 = 1000$
Differences:
$(x - y) = 333 - 333 = 0$
$(y - z) = 333 - 334 = -1$
$(z - x) = 334 - 333 = 1$
Substituting these values into the identity:
$= \frac{1}{2}(1000)[(0)^{2} + (-1)^{2} + (1)^{2}]$
$= \frac{1}{2}(1000)[0 + 1 + 1]$
$= \frac{1}{2}(1000)(2) = 1000$
241
DifficultMCQ
If $\frac{x-a^{2}}{b+c}+\frac{x-b^{2}}{c+a}+\frac{x-c^{2}}{a+b}=4(a+b+c),$ then $x$ is equal to:
A
$(a+b+c)^{2}$
B
$a^{2}+b^{2}+c^{2}$
C
$ab+bc+ca$
D
$a^{2}+b^{2}+c^{2}-ab-bc-ca$

Solution

(A) Given equation: $\frac{x-a^{2}}{b+c}+\frac{x-b^{2}}{c+a}+\frac{x-c^{2}}{a+b}=4(a+b+c)$
Let $x = (a+b+c)^{2}$.
Substituting $x$ in the equation:
$\frac{(a+b+c)^{2}-a^{2}}{b+c} + \frac{(a+b+c)^{2}-b^{2}}{c+a} + \frac{(a+b+c)^{2}-c^{2}}{a+b}$
Using the identity $A^{2}-B^{2} = (A-B)(A+B)$:
$= \frac{(a+b+c-a)(a+b+c+a)}{b+c} + \frac{(a+b+c-b)(a+b+c+b)}{c+a} + \frac{(a+b+c-c)(a+b+c+c)}{a+b}$
$= \frac{(b+c)(2a+b+c)}{b+c} + \frac{(a+c)(a+2b+c)}{c+a} + \frac{(a+b)(a+b+2c)}{a+b}$
$= (2a+b+c) + (a+2b+c) + (a+b+2c)$
$= 4a+4b+4c = 4(a+b+c)$
Since the expression satisfies the equation,$x = (a+b+c)^{2}$.
242
MediumMCQ
If $(x-a)(x-b)=1$ and $a-b+5=0,$ then the value of $(x-a)^{3}-\frac{1}{(x-a)^{3}}$ is:
A
$-125$
B
$1$
C
$125$
D
$140$

Solution

(D) Given $(x-a)(x-b)=1$,we can write $(x-b) = \frac{1}{x-a}$.
We are given $a-b+5=0$,which implies $a-b = -5$,or $b-a = 5$.
We need to find the value of $(x-a)^{3}-\frac{1}{(x-a)^{3}}$.
Substitute $\frac{1}{x-a} = x-b$ into the expression:
$(x-a)^{3} - (x-b)^{3}$.
Using the identity $A^3 - B^3 = (A-B)(A^2 + AB + B^2)$ or simply substituting $x-b = x-a + (a-b)$:
Let $u = x-a$. Then $x-b = u + (a-b) = u - 5$.
So,the expression becomes $u^3 - (u-5)^3$.
Expanding this: $u^3 - (u^3 - 15u^2 + 75u - 125) = 15u^2 - 75u + 125$.
Alternatively,using the given $(x-a)(x-b)=1$:
$u(u-5) = 1 \implies u^2 - 5u = 1$.
We want $u^3 - (u-5)^3 = u^3 - (u^3 - 3u^2(5) + 3u(25) - 125) = 15u^2 - 75u + 125$.
$= 15(u^2 - 5u) + 125$.
Substituting $u^2 - 5u = 1$:
$= 15(1) + 125 = 15 + 125 = 140$.
243
EasyMCQ
The value of $\sqrt{2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \ldots}}}}}}$ is
A
$2$
B
$2^{2}$
C
$2^{3}$
D
$2^{5}$

Solution

(A) Let $x = \sqrt{2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \ldots}}}}$.
Squaring both sides,we get $x^{2} = 2 \sqrt[3]{4 \sqrt{2 \sqrt[3]{4 \ldots}}}$.
Now,cubing both sides,we get $(x^{2})^{3} = 2^{3} \times 4 \times \sqrt{2 \sqrt[3]{4 \ldots}}$.
This simplifies to $x^{6} = 8 \times 4 \times x$.
$x^{6} = 32x$.
Since $x \neq 0$,we divide by $x$ to get $x^{5} = 32$.
$x^{5} = 2^{5}$,which implies $x = 2$.
244
DifficultMCQ
The value of $\left\{\frac{3 \sqrt{2}}{(\sqrt{3}+\sqrt{6})}-\frac{4 \sqrt{3}}{(\sqrt{6}+\sqrt{2})}+\frac{\sqrt{6}}{(\sqrt{2}+\sqrt{3})}\right\}$ is:
A
$\sqrt{2}$
B
$0$
C
$\sqrt{3}$
D
$\sqrt{6}$

Solution

(B) To solve the expression,we rationalize each term individually:
$1$. $\frac{3 \sqrt{2}}{\sqrt{6}+\sqrt{3}} = \frac{3 \sqrt{2}(\sqrt{6}-\sqrt{3})}{6-3} = \frac{3 \sqrt{2}(\sqrt{6}-\sqrt{3})}{3} = \sqrt{2}(\sqrt{6}-\sqrt{3}) = \sqrt{12}-\sqrt{6} = 2 \sqrt{3}-\sqrt{6}$
$2$. $\frac{4 \sqrt{3}}{\sqrt{6}+\sqrt{2}} = \frac{4 \sqrt{3}(\sqrt{6}-\sqrt{2})}{6-2} = \frac{4 \sqrt{3}(\sqrt{6}-\sqrt{2})}{4} = \sqrt{3}(\sqrt{6}-\sqrt{2}) = \sqrt{18}-\sqrt{6} = 3 \sqrt{2}-\sqrt{6}$
$3$. $\frac{\sqrt{6}}{\sqrt{3}+\sqrt{2}} = \frac{\sqrt{6}(\sqrt{3}-\sqrt{2})}{3-2} = \sqrt{6}(\sqrt{3}-\sqrt{2}) = \sqrt{18}-\sqrt{12} = 3 \sqrt{2}-2 \sqrt{3}$
Substituting these back into the original expression:
$(2 \sqrt{3}-\sqrt{6}) - (3 \sqrt{2}-\sqrt{6}) + (3 \sqrt{2}-2 \sqrt{3})$
$= 2 \sqrt{3} - \sqrt{6} - 3 \sqrt{2} + \sqrt{6} + 3 \sqrt{2} - 2 \sqrt{3}$
$= (2 \sqrt{3} - 2 \sqrt{3}) + (-\sqrt{6} + \sqrt{6}) + (-3 \sqrt{2} + 3 \sqrt{2})$
$= 0 + 0 + 0 = 0$
245
DifficultMCQ
If $a^{2}+b^{2}-c^{2}=2(a-b-c)-3,$ then the value of $4a-3b+5c$ is
A
$2$
B
$3$
C
$5$
D
$6$

Solution

(A) Given the equation: $a^{2}+b^{2}-c^{2}=2(a-b-c)-3$
Rearranging the terms: $a^{2}+b^{2}-c^{2}-2a+2b+2c+3=0$
Note: There is a sign correction required in the original equation to make it solvable as a sum of squares. Assuming the equation is $a^{2}+b^{2}+c^{2}=2(a-b-c)-3$:
$a^{2}-2a+1 + b^{2}+2b+1 + c^{2}+2c+1 = 0$
$(a-1)^{2} + (b+1)^{2} + (c+1)^{2} = 0$
Since the sum of squares is zero,each term must be zero:
$a-1=0 \Rightarrow a=1$
$b+1=0 \Rightarrow b=-1$
$c+1=0 \Rightarrow c=-1$
Now,calculate $4a-3b+5c$:
$4(1) - 3(-1) + 5(-1) = 4 + 3 - 5 = 2$
246
DifficultMCQ
If $2x + \frac{2}{x} = 3$,then the value of $x^3 + \frac{1}{x^3} + 2$ is
A
$-\frac{9}{8}$
B
$-\frac{25}{8}$
C
$\frac{7}{8}$
D
$11$

Solution

(C) Given: $2x + \frac{2}{x} = 3$
Divide the entire equation by $2$:
$x + \frac{1}{x} = \frac{3}{2}$
Now,cube both sides using the identity $(a+b)^3 = a^3 + b^3 + 3ab(a+b)$:
$(x + \frac{1}{x})^3 = (\frac{3}{2})^3$
$x^3 + \frac{1}{x^3} + 3(x)(\frac{1}{x})(x + \frac{1}{x}) = \frac{27}{8}$
Substitute $x + \frac{1}{x} = \frac{3}{2}$ into the equation:
$x^3 + \frac{1}{x^3} + 3(1)(\frac{3}{2}) = \frac{27}{8}$
$x^3 + \frac{1}{x^3} + \frac{9}{2} = \frac{27}{8}$
$x^3 + \frac{1}{x^3} = \frac{27}{8} - \frac{9}{2} = \frac{27 - 36}{8} = -\frac{9}{8}$
Finally,calculate the value of $x^3 + \frac{1}{x^3} + 2$:
$-\frac{9}{8} + 2 = \frac{-9 + 16}{8} = \frac{7}{8}$
247
DifficultMCQ
Out of the given responses,one of the factors of $(a^{2}-b^{2})^{3}+(b^{2}-c^{2})^{3}+(c^{2}-a^{2})^{3}$ is:
A
$(a+b)(a-b)$
B
$(a+b)(a+b)$
C
$(a-b)(a-b)$
D
$(b-c)(b-c)$

Solution

(A) Let $x = a^{2}-b^{2}$,$y = b^{2}-c^{2}$,and $z = c^{2}-a^{2}$.
Then,$x+y+z = (a^{2}-b^{2}) + (b^{2}-c^{2}) + (c^{2}-a^{2}) = 0$.
We know the algebraic identity: If $x+y+z = 0$,then $x^{3}+y^{3}+z^{3} = 3xyz$.
Substituting the values,we get:
$(a^{2}-b^{2})^{3}+(b^{2}-c^{2})^{3}+(c^{2}-a^{2})^{3} = 3(a^{2}-b^{2})(b^{2}-c^{2})(c^{2}-a^{2})$.
Expanding the terms using the difference of squares formula $a^{2}-b^{2} = (a-b)(a+b)$:
$= 3(a-b)(a+b)(b-c)(b+c)(c-a)(c+a)$.
Thus,$(a+b)(a-b)$ is one of the factors.
248
MediumMCQ
If $x=\sqrt[3]{5}+2,$ then the value of $x^{3}-6 x^{2}+12 x-13$ is
A
$-1$
B
$1$
C
$2$
D
$0$

Solution

(D) Given $x = \sqrt[3]{5} + 2$.
Subtracting $2$ from both sides,we get $x - 2 = \sqrt[3]{5}$.
Now,cubing both sides of the equation:
$(x - 2)^3 = (\sqrt[3]{5})^3$
Using the algebraic identity $(a - b)^3 = a^3 - 3a^2b + 3ab^2 - b^3$,we expand the left side:
$x^3 - 3(x^2)(2) + 3(x)(2^2) - 2^3 = 5$
$x^3 - 6x^2 + 12x - 8 = 5$
To find the value of $x^3 - 6x^2 + 12x - 13$,we subtract $5$ from both sides of the equation:
$x^3 - 6x^2 + 12x - 8 - 5 = 0$
$x^3 - 6x^2 + 12x - 13 = 0$.
249
DifficultMCQ
The value of $(3+\sqrt{8})+\frac{1}{3-\sqrt{8}}-(6+4 \sqrt{2})$ is
A
$8$
B
$1$
C
$\sqrt{2}$
D
$0$

Solution

(D) First,rationalize the denominator of the fraction $\frac{1}{3-\sqrt{8}}$:
$\frac{1}{3-\sqrt{8}} = \frac{1 \times (3+\sqrt{8})}{(3-\sqrt{8})(3+\sqrt{8})} = \frac{3+\sqrt{8}}{3^2 - (\sqrt{8})^2} = \frac{3+\sqrt{8}}{9-8} = 3+\sqrt{8}$.
Now,substitute this back into the original expression:
$(3+\sqrt{8}) + (3+\sqrt{8}) - (6+4\sqrt{2})$.
Since $\sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2}$,we can rewrite the expression as:
$(3+2\sqrt{2}) + (3+2\sqrt{2}) - (6+4\sqrt{2})$.
$= 6 + 4\sqrt{2} - 6 - 4\sqrt{2} = 0$.
250
DifficultMCQ
If $x>1$ and $x^{2}+\frac{1}{x^{2}}=83,$ then $x^{3}-\frac{1}{x^{3}}$ is
A
$764$
B
$750$
C
$756$
D
$760$

Solution

(C) Given $x^{2}+\frac{1}{x^{2}}=83$.
We know that $(x-\frac{1}{x})^{2} = x^{2}+\frac{1}{x^{2}}-2$.
Substituting the value,we get $(x-\frac{1}{x})^{2} = 83-2 = 81$.
Since $x>1$,$x-\frac{1}{x}$ must be positive,so $x-\frac{1}{x} = \sqrt{81} = 9$.
Now,using the identity $(x-\frac{1}{x})^{3} = x^{3}-\frac{1}{x^{3}}-3(x-\frac{1}{x})$.
Substituting the values,$9^{3} = x^{3}-\frac{1}{x^{3}}-3(9)$.
$729 = x^{3}-\frac{1}{x^{3}}-27$.
Therefore,$x^{3}-\frac{1}{x^{3}} = 729+27 = 756$.

Number system — Simplification · Frequently Asked Questions

1Are these Number system 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 Number system 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.