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)