3(x²-2xy)-2(-3xy+y²)
-3(xy-2x²)-[y²-(5xy-4x²)+2xy]
已知x:y=3:2,求(x²+3xy)/(xy+2xy)
合并同类项:(2xy²+3xy²)-(6x²y-3xy²)
(2x²y-3xy²)-3(x²y-2xy²)+2(x²y-4xy
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
(3x²y-xy²+2xy)/二分之一xy
先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y
3xy²-[xy-2(xy-3/2x²y)+3xy²]+3xy²,其中x=3,y
已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
化简4xy-3y²-3x²+xy-3xy-2x²+x²-2y²
已知x/y=3,求(x²+2xy-3xy²)/(x²-xy+y²)