2x+5y=1 两边同除xy得2/y+5/x=1/xy
(1+1/x)(1+1/y)
=1+1/x+1/y+1/xy
=1+1/x+1/y+2/y+5/x
=1+6/x+3/y
=1+(2x+5y)(6/x+3/y)
=28+6(5y/x+x/y)≥28+12√5
(1+1/x)(1+1/y)的最小值是28+12√5
2x+5y=1 两边同除xy得2/y+5/x=1/xy
(1+1/x)(1+1/y)
=1+1/x+1/y+1/xy
=1+1/x+1/y+2/y+5/x
=1+6/x+3/y
=1+(2x+5y)(6/x+3/y)
=28+6(5y/x+x/y)≥28+12√5
(1+1/x)(1+1/y)的最小值是28+12√5