Question

f(3)= -5, g(3)=9, f'(3)=8 and g'(3)= -4
how do I find (fg)'(3)
(f/g)'(3)
and (f/(f-g))'(3)??

Answer 1

use the rules for derivatives of products and quotients
for example, the simplest one is
\[(fg)'=f'g+g'f=8\times 9+(-4)\times (-5)\] others are similar. rules plus arithmetic