x+y=5 xy=8 求x^2+y^2

已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知(x+y):y=8:3,求2x+5y/3x-y和x^2-xy/y^2+3xy的值 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 已知xy/x+y=3,求代数式2x-5xy+2y/x-3xy+y 已知xy/x+y=2,求代数式3x-5xy+3y/-x+2xy-y的值 已知xy=2(x+y),求(5x-xy+5y)/(3xy-x-y)的值 已知x-y=2xy,求代数式3x-5xy-3y/x+xy-y的值 已知X+Y=2XY,求4X-5XY+4Y 除以X+XY+Y 的值 已知X+Y分之XY=2,求-X+3XY-Y分之3X+5XY+3Y 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y* 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+2(xy+y)的值