if f(x)=x^3+5x, then f'(2)=

if f(x)=cos(2x), then f'(pi/4)

derivatives and anti derivatives

please help

f(x)=x^3+5x

f'=2x^2+5
put in x=2

d (cos2x)/dx=-2sin2x

You need to examine why these are causing you difficulty,they are very elementary questions.