3x²-[1/2x²y-(2xy+2x²-x²y)-(2x²y+xy)
x-y/x²÷x²-2xy+y²/xy*(xy-x²)
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
【(1)/(x-y)+(1)/(x-y)】÷(2x)/(x²-2xy+y²)
急![(3x+y)²-3(3x-y)(x+y)-(x-3y)(x+3y)]÷(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
下列多项式:(1)x²+xy-y²;(2)-x²+2xy-y²;(3)xy+x&
计算:x²+2xy+y²/xy-y².x²-2xy+y²/xy+y
若x=1/2,y=1 求x(x²+xy+y²)-y(x²+xy+y²)+3xy(
(-x-2y)(x²-2xy+4y²)
x²-xy-2y²-x-y 因式分解