I've been stressing over these problems all week and my math professor has been always "busy" after school (I know... unreliable). So could anyone please help me with a few of these calculus problems and please explain how you got to the answer? I'm not going to type all of my homework because I also want to work on the rest of the problems so I am sure I am getting it.

Here are the directions and a couple problems:

Use the derivative formulas and the chain rule: if $\displaystyle (fog)(x) = f(g(x)) => (fog)'(x) = f'(g(x)) * g'(x)$ To find the derivative $\displaystyle \frac {dy}{dx}$ of each of the functions below.

10) $\displaystyle y = cos^2(2x)$

11) $\displaystyle y = x* sin(x^2)$

12) $\displaystyle y = \frac{x+sinx}{cosx}$

Could someone out there please help! We have a quiz on this on Friday and I need all the help I could get.