1. ## (fog)(x)

(fog)(x) =x2 + x. If g(2) = 4 and g’(2) = 5 , find f ‘ (4). Thank you.

2. ## Re: (fog)(x)

$f[g(x)]=x^2+x$

derivative of a composite function requires use of the chain rule ...

$f’[g(x)] \cdot g’(x) = 2x+1$

$f’[g(2)] \cdot g’(2) = 2(2)+1$

$f’(4) \cdot 5 = 5 \implies f’(4)=1$

3. ## Re: (fog)(x)

Thanks a lot.