已知2x^2+y^2-2xy-6x+9=0,求x+y-5的值

已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知x^2-6xy+9y^2=0,求(x-y)/(x+y) 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知(xy)/(x+y)=6求(3x-2xy+3y)/(-x+3xy-y)的值. 已知2x^2+6x+y^2=2xy-9,求x^y 已知x/y=2,求 [x^2-xy+3xy^2 ] / [ x^2+xy+6y^2]的值 已知x+y=6,xy=-3,则x^2y+xy^2=? 已知x+y=6,xy=4,求x^2y+xy^2的值~ 已知x+y=6,xy=-3,则x∧y+xy∧2= 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 已知x+y=1,xy=-2,则x²y+xy²-2xy 已知x^2+9y^2-2x-6y+2=0,求{-（xy/（x-y）^2}^4*(y^2-xy/x)^3*x^4/y^10/(x/xy-y^2)^5的值 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 已知1/x=1/y=6,则3x-2xy+3y/3xy+x+y=?已知1/x+1/y=6,则3x-2xy+3y/3xy+x+y=? 已知x-y=6,xy=-1,求(2x+3x-2xy)-(x+4y+xy)-(3yx-2x+2y)的值 已知x/y=2,求(x^2-xy+3y^2)/(x^2+xy+6y^2)的值