已知(x+y)²=1,(x-y)²=17求

已知x+y=1,xy=-二分之一,求x（x+y)(x-y)-x(x+y)² 已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y 已知x²+y²+5=2x+4y,求代数式（2x²-（x+y)(x-y))x((x+y-1) 已知实数x,y满足x²+y²-xy+2x-y+1=0 求x y 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知y+y'*x²=0,求y=? 已知{(x²+y²)-(x-y)²+2y(x-y)}÷4y=1,求4x²-y&# (1)已知x+y=6,x²-y²=5,求x-y的值（2）若x+y=3,x²+y² 已知x²+x*y=-1,x*y+y²=2,试求2x²-x*y-3y²的值 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x² 1：已知x=y+3,求代数式¼(x-y)²+(3/10)乘(x-y)+¾(x-y) 已知(2x)/(x²-y²)÷m=(1)/(x-y),求m