1. a) Calculate the partial derivatives for $\displaystyle f(x,y)=x^2 siny$ and prove that

b)If $\displaystyle x(u)=u^2$ and $\displaystyle y(u)=1/u$, calculate $\displaystyle df/du$ using the chain rule.

c)For $\displaystyle g(r)=r^4$ where $\displaystyle r=sqrt(x^2+y^2+z^2)$ use the chain rule to calculate $\displaystyle dg/dx$, $\displaystyle d^2g/dx2$ and $\displaystyle d^2g/dxdy$.

I am having a lot of trouble with this problem.