4xy-3x²-3xy-2y+2x² =-3x²+2x² +4xy-3xy-2y=-x² +xy-2yx³-2x²-x³+5x²+4=x³-x³-2x²+5x²+4=3x²+42x²+ax-y+6-2bx²+3x-5y-1=(2-2b)x&...看一看这道题5（x+y）²-3（x+y）³+3（x+y）²-5（x+y）³其中x=-3，y=2 合并同类项在求值和6x²y-2xy-3x²y²-7x-5yx-4y²x²-6x²y 其中|x+3|+（y-1/2）²=0 合并同类项在求值5（x+y）²-3（x+y）³+3（x+y）²-5（x+y）³=8（x+y）²-8（x+y）³x=-3，y=2所以原式=8+8=166x²y-2xy-3x²y²-7x-5yx-4y²x²-6x²y =6x²y-6x²y-2xy-5yx -3x²y²-4y²x²-7x=-7xy-7x²y²-7x由|x+3|+（y-1/2）²=0，得|x+3|=0，（y-1/2）²=0所以x=-3，y=1/2所以原式=21/2-63/4+21=63/4