已知x^2-xy=8,xy-y^2=3.则x^2-y^2=?,x^2-2xy+y^2=?

已知x-y=4xy，则2x+3xy-2yx-2xy-y 已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 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=2,则代数式3x-5y+8y/-x+3xy-y的值 已知：xy+x=-1，xy-y=-2． 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^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+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值! 已知x+y=3xy,求2x+2y-xy/x+y+2xy的值、