（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²
=-（2x-y+3z）(2x+y+3z)-(x+2y-3z)²
=-[(2x+3z)²-y²]-(x+2y)²+6z(x+2y)-9z²
=-4x²-12xz-9z²+y²-x²-4xy-4y²+6xz+12yz-9z²
=-5x²-3y²-18z²-6xz+12yz-4xy化简求值：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²,其中x=1,y=-1,z=1（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²=-（2x-y+3z）(2x+y+3z)-(x+2y-3z)²=-[(2x+3z)²-y²]-(x+2y)²+6z(x+2y)-9z²=-4x²-12xz-9z²+y²-x²-4xy-4y²+6xz+12yz-9z²=-5x²-3y²-18z²-6xz+12yz-4xy当x=1,y=-1，z=1时原式=-5-3-18-6-12+4=-40