Get Answers to all your Questions

header-bg qa

Please solve RD Sharma class 12 Chapter Maxima and Minima exercise Multiple choice question, question 36 maths textbook solution.

Answers (1)

Answer: (c) One Maximum and One Minimum

Hint: For local maxima or minima, we must have f'(x)=0.

Given: f(x)=2x^3-3x^2-12x+4

Solution:

Slope of the curve is given by,

f(x)=2x^3-3x^2-12x+4

f'(x)=6x^2-6x-12           

For maxima and minima f'(x)=0

\begin{aligned} &\Rightarrow 6 x^{2}-6 x-12=0 \\ &\Rightarrow x^{2}-x-2=0 \\ &\Rightarrow x=\frac{1 \pm \sqrt{1-4 \times 1 \times-2}}{2} \\ &x=\frac{1 \pm 3}{2} \\ &x=2,-1 \\ &f^{\prime \prime}(x)=12 x-6 \\ &f^{\prime \prime}(2)=12(2)-6=24-6=18>0 \end{aligned}

So, x = 2 is local minima.

f''(-1)=12(-1)-6=-12-6=-18<0

So, x = -1 is local maxima.

Therefore, One Maxima and One Minima is the answer.

Posted by

infoexpert24

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads