# Math Help - function problemss 31

1. ## function problemss 31

If F(x) = f( 2f( 4f( x ))), where f(0) = 0 and f '(0) = 3, find F '(0).

2. Try to find F'(x)...

3. i am learning derivatives rite now and i have to use the information available and solve it.. i don't have an idea.. confused.. can some one else please help me with it !!

4. Originally Posted by doboy
If F(x) = f( 2f( 4f( x ))), where f(0) = 0 and f '(0) = 3, find F '(0).
let $w=4f(x)$
$u=2f(w)$ then

$F(x)=f(u)$

Now by the chain rule you get

$\frac{dF}{dx}=\frac{df}{du}\frac{du}{dw}\frac{dw}{ dx}=...$