Describe the graph of each multivariable function. (a) f(x, y) = 3 - 2x + 5y (b) f(x, y) = V 16 - x2 -y2 Sketch the level curves for the function and given values of c. (a) f(x, y) = x2 - y?, c= -1,1 (b) f(x, y) = x2 + 4y', c =1,2,3,4