来自段洪秀的问题
已知3x2+xy-2y2=0,求(x+yx-y+4xyy2-x2)÷x2+2xy-3y2x2-9y2的值.
已知3x2+xy-2y2=0,求(x+yx-y+4xyy2-x2)÷x2+2xy-3y2x2-9y2的值.


已知3x2+xy-2y2=0,求(x+yx-y+4xyy2-x2)÷x2+2xy-3y2x2-9y2的值.
已知3x2+xy-2y2=0,求(x+yx-y+4xyy2-x2)÷x2+2xy-3y2x2-9y2的值.
原式=[(x+y)