1. Find the total differential (dz) of the following functions: ^^20a.^^20x=x\sin (y)-y\sin (x) \text { b. } z=(x+2)^{2}+\left(y^{2}-4\right)^{2} 2. Find the maximum and minimum values of f(x)=e^xy subject to the

constraint g(x, y) = x^3 + y^3 = 16.