x的平方+xy分之x+3y加xy+y的平方分之y-x分式
问题描述：
x的平方+xy分之x+3y加xy+y的平方分之y-x分式
答
(x+3y)/(x²+xy) +(y-x)/(xy+y²)
=(x+3y)[x(x+y)] -(x-y)/[y(x+y)]
=[(x+3y)y -x(x-y)]/[xy(x+y)]
=(xy+3y²-x²+xy)/[xy(x+y)]
=-(x²-2xy-3y²)/[xy(x+y)]
=-(x+y)(x-3y)/[xy(x+y)]
=(3y-x)/(xy)
=3/x - 1/y