已知x-y=8,xy=-15,则-2x²-2y²
已知x-5y=0,求分式x²-2xy+y²/3x+y × (y-x)的值
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
已知X/Y=2,则X²+2XY-3Y²/X²-XY+Y²=?
已知2x+2y=-5,则2x²+4xy+2y²-7=
已知x²-xy,xy-y²=-12,分别求式子x²-y²与x²-2xy
已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
已知:(x+2)²+|x+y-10|=0,求3x²y-[5x²y-﹙2xy-x²
已知x-y=4,xy=-2,则代数式(3x-4y+5xy)-(2x-3y-2xy)的值是多少
已知xy/x+y=2,则代数式3x-5y+8y/-x+3xy-y的值
已知(x-2y)=y(2y-x),则x²-y²/xy的值是?
已知2x=3y,求xy/x²+y² - y²/x²-y²的值
已知:x-2xy-8y=0(x≠0,y≠0),则代数式2x+3y/2y=