Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

Let $f(x)=e^x, x \in[0,1]$ then a number $c$ of the Lagrange's mean value theorem is

Options:

$\log _e(e-1)$

$\log _e(e+1)$

$\log _e e$

none of these

Correct Answer:

$\log _e(e-1)$

Explanation:

Clearly, $f(x)$ is continuous on $[0,1]$ and differentiable on $(0,1)$. Therefore, there exists $c \in(0,1)$ such that

$f^{\prime}(c)=\frac{f(1)-f(0)}{1-0} \Rightarrow e^c=e-1 \Rightarrow c=\log _e(e-1)$