Find fx(x,y) and fy(x,y). Then, find fx( - 1,4) and fy( - 4, 1). f ( x,y) = 4x2y's fx(x,y) = fy ( x,y) = fx (- 1,4) = (Simplify your answer.) fy (- 4,1) =(Simplify your answer.) Find all the second-order partial derivatives of the function f(x,y) = 8x2+ 4y + 9x2y2. 22f dyox by oxdy Find all points (x,y) where f(x,y) has a possible relative maximum or minimum. f ( x,y) = x2 - 3y+ 2x +6y-1 First, find the partial derivatives. 2 98 9 Using only the first-derivative test for functions of two variables, find all the points that are possibly a relative maximum or a relative minimum. (Type an ordered pair. Type an exact answer. Use a comma to separate answers as needed.)