化简2y²﹢6y-3y²-5y=
化简:1.2x²-y²+(2y²-3x²)-(2y²+x²)
已知X²-5XY+6Y²=0,求(X²+3XY)\2Y²的值
x/y=2,求分式x²-xy+3y²/x²+xy+6y²
已知x²+y²-4x+6y+13=0,求x²+2y/x²-3y²的值
|x+2y+3|+(2x+y)²=0求x²-xy+y²
已知关于x、y的方程组3(x²+y²)-5xy=6;2(x²+y²)+xy=17
已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy
已知2x²+3y²=6x 则x²+y²+2x的最大值
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²+3x-y.若x
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²-3x-y,若|
设A=2x²-3xy+y²-x+2y ,B=4x²-6xy+2y²+3x-y .
已知(x²+y²)(x²+y²-6)+9=0 ,求x²+y²