已知2x-3xy=6,3xy-2y=-2,那x-y=多少?

由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知x-y=4xy，则2x+3xy-2yx-2xy-y 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知x/y=2,求 [x^2-xy+3xy^2 ] / [ x^2+xy+6y^2]的值 已知x+xy=-2,xy-y=-6求代数式2x｛-4y-3[（x+xy）²+x]-½[（y-xy (1)已知x+y=6,xy=-3,x^2y+xy^2= 已知x+y=6,xy=-3,则x^2y+xy^2=? 已知x+y=6,xy=-3,则x^2y+xy^2= 已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2