The chain rule for partial derivatives Let f : R2 - R be a real-valued function of two variables defined by f(x, y) = y x and suppose a and y are real-valued functions of two variables defined by x (u, v) = v -u, y(u, v) = -u - v. Evaluate the following derivatives at (u, v) = (0, 1): of du (u,v)=(0,1) L of = av (u,v)=(0,1)