如果1/x+1/y=2,求3x+2xy+3y/2x-2xy+2y的值.
问题描述:
如果1/x+1/y=2,求3x+2xy+3y/2x-2xy+2y的值.
答
题写错了吧?2xy-2xy?
答
(3x+2xy+3y)/(2x-2xy+2y)=[xy(3/y+2+3/x)]/[xy(2/y-2+y/x)]
=[3(1/y+1/x)+2]/[2(1/y+1/x)-2]
=[3*2+2]/[2*2-2]
=8/2=4
答
4
答
3x+2xy+3y/2x-2xy+2y=3x+3y/2x+2y,打错了吧
答
1/x+1/y=2得 x+y=2xy
3x+2xy+3y=3x+x+y+3y=4(x+y)
2x-2xy+2y=2x-x-y+2y=x+y
原式=4(x+y)/(x+y)=4