2x 2 y 2 9 6x 2xy July 8, 2019 16 32 64 128 2x 2 y 2 6x 2xy 9 0 Cho xy thỏa mãn 2x 2 y 2 9 6x 2xy 2x 9 2x + y = 4 6xy - 4y + 6 - 9x
