Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

The function $f(x)=\tan ^{-1}(\tan x)$, is

Options:

everywhere continuous

discontinuous at $x=\frac{n \pi}{2}, n \in Z$

not differentiable at $x=(2 n+1) \frac{\pi}{2}, n \in Z$ such that f'(x) = 1 for all $x \in R-\left\{(2 n+1) \frac{\pi}{2}, n \in Z\right\}$

everywhere continuous and differentiable such that f'(x) = 1 for all $x \in R$

Correct Answer:

not differentiable at $x=(2 n+1) \frac{\pi}{2}, n \in Z$ such that f'(x) = 1 for all $x \in R-\left\{(2 n+1) \frac{\pi}{2}, n \in Z\right\}$

Explanation:

The graph of the function $f(x)=\tan ^{-1}(\tan x)$ is as given in Figure.

It is evident from the curve y = f(x) that f(x) is discontinuous and hence non-differentiable at $x=(2 n+1) \frac{\pi}{2}, n \in Z$ such that f'(x) = 1 for all $x \in R-\left\{(2 n+1) \frac{\pi}{2}, n \in Z\right\}$.