Question

已知xy分之x＋y等于3,求2x－3xy＋2y 分之﹣x＋3xy－y的值.快

Answer 1

(x+y)/(xy)=3,即 1/x+1/y=3

(-x+3xy-y)/(2x-3xy+2y)

=(-1/y+3-1/x)/(2/y-3+2/x) (分子,分母同时除以xy)

=(-3+3)/(6-3)

=0