+2y=1 xy+x=1 3x- =5 x2-2=3xxy=1 2x(y+1)=c 2x-y=1 x+y=0 的解谁知道

先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知实数x,y满足(x2)+(y2)-xy+2x-y+1=0,求x,y的值 已知实数x、y满足X2+y2-xy+2x-y+1=0,试求x、y的值 若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( ) x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 若x2-2xy-y2-x+Y-1=0 求x-y的值 (x+y)(x+y+1)=0 求x2+y2+2xy的值 已知1/x+1/y=5,求(2x-3y+2y)/(x+2xy+y)的值 已知x/1-y/1=3,则5x+xy-5y/x+2y-y的值为 1/x-1/y=3,求2x+3xy-2y/x-y 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y=