## anonymous 5 years ago find the first derivative of y=1-cos2x + 2cos^2x.

1. anonymous

you have to use chain rule with the cos: $\cos(ax) dx= asin(ax)$

2. anonymous

ok, thank you!

3. anonymous

np

4. dumbcow

just a note: d/dx cos(x) = -sin(x) so above there should be a neg sign in front of asin(ax)

5. anonymous

ops, confused with integrals hehe. Thanks cow

6. anonymous

$y=1 - \text{Cos}[2*x] + 2*\text{Cos}[x]^2 = 2$ Derivative of 2 is zero.