(5x²y-2xy²-3xy)-(2xy+5x²y-2xy²),x=-1/5,y
已知X²-5XY+6Y²=0,求(X²+3XY)\2Y²的值
1-x²+2xy-y²
计算:(1).(-2xy²)*(3x²y)²
求多项式2x²-3xy+y²-2xy-2x²+5xy-2y+1的值,其中x=22/7,y=
问已知x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x&su
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
试找出多项式3x²y-4xy²-3+5x²y+2xy²+5x的三次方y+1中的同
已知关于x、y的方程组3(x²+y²)-5xy=6;2(x²+y²)+xy=17
|x+2y+3|+(2x+y)²=0求x²-xy+y²
先化简,再求值:3xy²(-x²y+2x³y²)-4xy(-xy²)·