化简4xy-3y²-3x²+xy-3xy-2x²+x²-2y²
化简4xy-3y²-3x²+xy-3xy-2x²+x²-2y²
-3(xy-2x²)-[y²-(5xy-4x²)+2xy]
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
(2x²y-3xy²)-3(x²y-2xy²)+2(x²y-4xy
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
已知x:y=3:2,求(x²+3xy)/(xy+2xy)
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
化简-3x²y+2x²y+3xy²-2xy²
化简(3X²-XY+Y²)-5(X²-XY+2Y²)
-4x²y-8xy²+2x²y-3xy²
已知x/y=3,求(x²+2xy-3xy²)/(x²-xy+y²)
下列多项式:(1)x²+xy-y²;(2)-x²+2xy-y²;(3)xy+x&