5x²y-[2²y-(3xy-xy²)-3x²]-2xy²-y

-3(xy-2x²)-[y²-(5xy-4x²)+2xy] 3x²y+xy²-[2xy²-4x²y+（x²y-2xy²） (2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy&# 先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y 化简（3X²-XY+Y²）-5(X²-XY+2Y²） 计算：(xy-x²)×x-y/xy 计算：x²+2xy+y²/xy-y².x²-2xy+y²/xy+y&# x-y/x²÷x²-2xy+y²/xy*（xy-x²） 已知x:y=3:2,求(x²+3xy)/(xy+2xy) 计算 2xy[4x²y²-3y（xy+x²y）-xy²] 已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 -2y³+（3xy²-x²y）-2（xy²-y³）