# Finding derivatives of a function

• May 11th 2010, 10:38 AM
fabxx
Finding derivatives of a function
The problem is g(x)= f(square root f(x)+4) I hand wrote the problem and my work and attached it to avoid any confusion.

More importantly, any tips when dealing with these kind of problem? I had trouble with this at first. Thank you
• May 11th 2010, 11:23 AM
skeeter
Quote:

Originally Posted by fabxx
The problem is g(x)= f(square root f(x)+4) I hand wrote the problem and my work and attached it to avoid any confusion.

More importantly, any tips when dealing with these kind of problem? I had trouble with this at first. Thank you

$g(x) = f[\sqrt{f(x)+4}]$

$g'(x) = f'[\sqrt{f(x)+4}] \cdot \frac{f'(x)}{2\sqrt{f(x)+4}}$

evaluate $g'(3)$
• May 11th 2010, 11:46 AM
fabxx
Ah I forgot the 4.

Can you help me check again if its correct (the attachment)
• May 12th 2010, 04:00 AM
HallsofIvy
Yes, that is correct.