已知1/x+1/y=2,则3x+xy+3y/x-5xy+y的值是
问题描述:
已知1/x+1/y=2,则3x+xy+3y/x-5xy+y的值是
答
(3x+xy+3y)/(x-5xy+y)
=(3/y+1+3/x)/(1/y-5+1/x)
=(6+1)/(2-5)
=7/(-3)
=-7/3