已知正数x,y满足=1,则xy有(    )A.最小值12                  

已知正数x,y满足=1,则xy有(    )

A.最小值12                         B最大值12

C.最小值144                        D.最大值144

答案

解析

:由=1得xy=9x+4y≥,解得xy≥144.当且仅当x=8,y=18时取等号.选C.

答案

:C

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