3)f=x12 x2 x32 x4-2x1x2 4x1x3-2x1x4 6x2x3-4x2x4 3)f=x12 x2 x32 x4-2x1x2 4x1x3-2x1x4 6x2x3-4x2x4 发布时间:2025-07-20 20:26:44