已知x分之1+y分之1=3,求2x-3xy+2y分之x+xy+y.

问题描述:

已知x分之1+y分之1=3,求2x-3xy+2y分之x+xy+y.

1/x+1/y=(x+y)/xy=3
所以x+y=3xy
(x+xy+y)/(2x-3xy+2y)
=[(x+y)+xy]/[2(x+y)-3xy]
=4xy/3xy
=4/3