Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Applications of Derivatives

Question:

Let $f(x)=\left\{\begin{array}{l}|x| & \text { for } 0<|x| \leq 2 \\ 0 & \text { for } x=0\end{array}\right.$ Then at x = 0, f has

Options:

a local maximum

no local maximum

a local minimum

no extremum

Correct Answer:

no extremum

Explanation:

$f(x)=\left\{\begin{array}{l}-x,-2<x<0 \\ 0, x=0 \\ x, 0<x<2\end{array}\right.$

f'(x) does not exist as f''(0) = –1 and f'(0+) = 1.