Find both the maximum value and the minimum value of $3x^{4}-8x^{3}+12x^{2}-48x+25$ on the interval $[0,3]$.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(A) Let $f(x) = 3x^{4}-8x^{3}+12x^{2}-48x+25$.
First,find the derivative $f'(x) = 12x^{3}-24x^{2}+24x-48$.
Set $f'(x) = 0$ to find critical points: $12(x^{3}-2x^{2}+2x-4) = 0$.
Factoring the cubic: $12[x^{2}(x-2)+2(x-2)] = 0$,which gives $12(x-2)(x^{2}+2) = 0$.
The only real critical point in the interval $[0,3]$ is $x=2$.
Now,evaluate $f(x)$ at the critical point and the endpoints of the interval:
At $x=0$: $f(0) = 3(0)^{4}-8(0)^{3}+12(0)^{2}-48(0)+25 = 25$.
At $x=2$: $f(2) = 3(2)^{4}-8(2)^{3}+12(2)^{2}-48(2)+25 = 3(16)-8(8)+12(4)-96+25 = 48-64+48-96+25 = -39$.
At $x=3$: $f(3) = 3(3)^{4}-8(3)^{3}+12(3)^{2}-48(3)+25 = 3(81)-8(27)+12(9)-144+25 = 243-216+108-144+25 = 16$.
Comparing these values: $25, -39, 16$.
The maximum value is $25$ at $x=0$ and the minimum value is $-39$ at $x=2$.

Explore More

Similar Questions

Find two positive numbers whose sum is $16$ and the sum of whose cubes is minimum.

For the function $f(x) = (1 + \frac{1}{x})^x$,which of the following is true?

The values of $x$ at the stationary points of $f(x)=x^3+3x^2-2$ are

The minimum value of the polynomial $x(x + 1)(x + 2)(x + 3)$ is

If $f(x) = \sin x - x \cos x$ has a maximum at $x = n\pi$,then which of the following is true?

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 exam papers from 7.5L+ questions 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