Limits Continuity And Differentiability Question 87

Question: If $ f(0)=0,f’(0)=2 $ , then the derivative of $ y=f(f(f(f(x))) $ at $ x=0 $ is

Options:

A) 2

B) 8

C) 16

D) 4

Show Answer

Answer:

Correct Answer: C

Solution:

$ y’(x)=f’(f(f(f(x))))f’(f(f(x)))f’(f(x))f’(x) $

$ \Rightarrow y’(0)=f’(f(f(f(0)))f’(f(f(0)))f’(f(0))f’(0) $

$ =f’(f(f(0)))f’(f(0)))f’(0)f’(0) $

$ =f’(f(0))f’(0)f’(0)f’(0) $

$ =f’(0)f’(0)f’(0)f’(0)={{(f’(0))}^{4}}=2^{4}=16 $ .