-4x-2y+9x+7y Suppose that f(x, y) = e then find the discriminant of f. - Let f(x, y) = x + 2y 32xy. List the critical points: The critical point at the origin is a Select an answer The critical point with positive x value is a Select an answer C Let f(x, y) = x - y + 6xy. List the critical points: The critical point at the origin is a Select an answer C The critical point with negative y value is a Select an answer