JEE PYQ: Limits Question 23
Question 23 - 2019 (09 Apr Shift 2)
If $f : \mathbb{R} \to \mathbb{R}$ is a differentiable function and $f(2) = 6$, then $\lim_{x \to 2} \frac{\int_6^{f(x)} \frac{2t,dt}{x-2}}{1}$ is:
(1) $24f’(2)$
(2) $2f’(2)$
(3) $0$
(4) $12f’(2)$
Show Answer
Answer: (4)
Solution
Using L’Hospital rule and Leibnitz theorem: $\lim_{x\to 2}\frac{2f(x)f’(x) - 0}{1} = 2f(2)f’(2) = 2 \cdot 6 \cdot f’(2) = 12f’(2)$.