计算:4xy²-3x²y-{3x²y-[2xy²-4x²y+2(x&s
计算:(1).(-2xy²)*(3x²y)²
3x²-4xy+y²
先化简,再求值:3xy²(-x²y+2x³y²)-4xy(-xy²)·
x²-4y²/x²+2xy+y²÷x+2y/2x²+2xy
1-x²+2xy-y²
因式分解 x²-3xy+2y²+x-2
计算:3(2x²-3xy²)-2(2xy²-3x²y)
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²+3x-y.若x
|x+2y+3|+(2x+y)²=0求x²-xy+y²
已知x/y=3,求x²+2xy-3y²/x²-2xy+y²
已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
x/y=2,求分式x²-xy+3y²/x²+xy+6y²