Q. Let $f:R \rightarrow R$ be a differentiable function and$f(1) = 4$. Then, the value of $\lim_{x \rightarrow 1}\frac{\int_{4}^{f\ (x)}{2t}}{x - 1}dt$, if $f^{'}(1) = 2$ is

A) 16
B) 8
C) 4
D) 2
Explanation

(a)
$\lim_{x \rightarrow 1}\frac{\int_{4}^{f\ (x)}{2t\ dt}}{x - 1} = \lim_{x \rightarrow 1}\frac{2f(x).f^{'}(x)}{1}$
$= 2f(1).f^{'}(1) = 16$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.