The chain rule for partial derivatives Let f : R - R be a real-valued function of two variables defined by f(x, y) = ya' and suppose x and y are real-valued functions of two variables defined by x(u, v) = 2u - v, y(u, v) = 2u + v. Evaluate the following derivatives at (u, v) = (-1, 1): of du (u,v)=(-1,1) of = av (u,v)=(-1,1)