Question

Given f and g are differentiable functions and
f(a)=-4, g(a)=c, g(c)=10, f(c)=15
f'(a)=8, g'(a)=b, g'(c)=5, f'(c)=6

If h(x)=f(g(x)). find h'(a)?


i'm not really sure how to get the answer. g'(a)=b, f'(b)=? How do i go about doing this. My reasoning must be wrong.

h'(x)= f'(g(x))*g'(x)
if x=a
h'(a)=f'(g(a))*g'(a)
=f'(c) * b = 6b

check my thinking.