Q. If $f(1) = 1,\ f^{'}(1) = 2$, then $\lim_{x \rightarrow 1}\frac{\sqrt{f(x)} - 1}{\sqrt{x} - 1}$ is

A) 2
B) 4
C) 1
D) 1/2
Explanation

(a)
$\lim_{x \rightarrow 1}\frac{\sqrt{f(x)} - 1}{\sqrt{x} - 1} = \lim_{x \rightarrow 1}\frac{\sqrt{x} - f'(x)}{\sqrt{f(x)}}$ [by L’ Hospital’s rule]
$= \frac{1.f(1)}{f(1)} = \frac{2}{1} = 2$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

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