(2)f=x1 3x2 9x3 19x4-2x1x2 4x1x3 2x1x4-6x212x3x4 (2)f=x1 3x2 9x3 19x4-2x1x2 4x1x3 2x1x4-6x212x3x4 发布时间:2025-07-11 17:59:02