化简求值 (2x³-xyz)-2(x³-y³+xyz)+(xyz-3y³) x=1 y=-2 z=-3
问题描述:
化简求值 (2x³-xyz)-2(x³-y³+xyz)+(xyz-3y³) x=1 y=-2 z=-3
答
(2x³-xyz)-2(x³-y³+xyz)+(xyz-3y³)
= 2x³-xyz-2x³+2y³-2xyz+xyz-3y³
=-y³-2xyz
=-y(y²+2xz)
=2×(4-6)
=-4