x^2-2xy+y^2=1 2x^2-5xy-3y^2=0

已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= .(x+y-2)(x+y-2xy)+(xy-1)^2 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+2(xy+y)的值 已知x+y=1,xy=-2,则x²y+xy²-2xy 1-2/x+y=xy,4y+6x=xy.求xy的解? 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 已知x+y=1,xy=1/5,则x^2y=xy^2 若x-y=1,xy=5,则x^2y-xy^2＝ （x^2+xy/x-y)/（xy/x-y)计算 5xy平方-2x平方y+[3xy平方-(4xy-2x平方y-2x平方y)],其中x=-2,y=-1求值 先化简,再求值:{xy(x²-3y)+3xy²}(-2xy)+x³y²(2x-y),其中x=-1/2,y=-5 【数学】已知 1/x-1/y=3 求 5x-xy-5y / x-2xy-y=?已知 1/x=1/y 求 2x-3xy-2y / x-2xy-y=? 已知1/x+1/y=5,求x+y+3xy/2x-4xy+2y的值,已知1/x+1/y=5,x+y+3xy/2x-4xy+2y的值, (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1)