1/2x^2+xy+1/2y^2=8,xy=3求x-y

.(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,则x²y+xy²-2xy 1-2/x+y=xy,4y+6x=xy.求xy的解? (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) （x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2 因式分解（x+y-2xy)(x+y-2)+(xy-1)^2设x+y=a,xy=b, 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 已知xy-x-y=11,求(xy-1)^2+(x+y-2)(x+y-2xy)的值. 已知1/x+1/y=8,求2x-3xy+2y/x+2xy+y的值 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= x+y=1,xy=-2求(x²+y²+xy)/(x²+y²-xy) 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 1-x-2Xy-y=1-() (8xy-3x平方)-5xy-2(3xy-2x平方),其中,x=2,y=-1 计算3xy[2xy-x(y-2)+x-1] (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值