3y/x*x-y*y+x/x*x-2xy+y*y+6y*y/x*x*x-x*x*y-xy*y+y*y*y等于多少?
问题描述：
3y/x*x-y*y+x/x*x-2xy+y*y+6y*y/x*x*x-x*x*y-xy*y+y*y*y等于多少?
答
3y/(x^2-y^2)+x/(x^2-2xy+y^2)+6y^2/(x^3-x^2y-xy^2+y^3)=3y/[(x+y)(x-y)]+x/(x-y)^2+6y^2/[(x-y)^2(x+y)]=3y(x-y)/[(x-y)^2(x+y)]+x(x+y)/[(x-y)^2(x+y)]+6y^2/[(x-y)^2(x+y)]=[3y(x-y)+x(x+y)+6y^2]/[(x-y)^2(x+y)...