(a) Find the equation of the tangent plane to z = xey at the point (2,0,2). (b) Find the linear approximation to f(x, y) = xey at the point (2, 0). (a) Show that f(x, y) = 5x+4y is differentiable. (b) Find the equation of the tangent plane to f at the point (2, 1, 14). (c) Find the linear approximation to f at the point (2, 1)