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

相关题目

一个全自动洗衣机的脱水筒的直径为38 cm，脱水筒工作时的转

一个全自动洗衣机的脱水筒的直径为38 cm，脱水筒工作时的转速为820 r/min，脱水筒工作时衣服所具有的向心加速度大小为多大？是重力加速度的几倍？为

— Could you take my place and go to meet Smith? — _______. — He i

— Could you take my place and go to meet Smith? — _______. — He is a tall man wearing short hair. A. Why me this time? B. Are

Please post this letter for me, as I’m ______ busy ______ go out.A. so; that �

Please post this letter for me, as I’m ______ busy ______ go out.A. so; that B. enough; toC. such; that D. too; to

阅读下面的文章，然后回答第14－16题。（7分）塑料瓶装水

阅读下面的文章，然后回答第14－16题。（7分）塑料瓶装水真的“干净”吗 ①出门在外，口渴的时候我们都习惯买一瓶水喝，瓶装水给我们的印

p{font-size:10.5pt;line-height:150%;margin:0;padding:0;}td{font-size:10.5pt;}(08

p{font-size:10.5pt;line-height:150%;margin:0;padding:0;}td{font-size:10.5pt;}(08浙江淳安县三校联考)燃烧1g乙炔（C2H2）生成二氧化碳和液态水，放出热量50kJ, 则这一反应

A big earthquake __________7.1 on the Richter scale struck Yushu, knocking dow

A big earthquake __________7.1 on the Richter scale struck Yushu, knocking down buildings and causing more than two thousands people to lose their lives． A. measured �

下列关于化学方程式的意义的叙述中错误的是( ) A.

下列关于化学方程式的意义的叙述中错误的是( ) A. 化学方程式可以表示各种物理变化 B．化学方程式可以表示各反应物和各生成物之间的质

The famous actor played _____ important role in_____ movie Beautiful life.

The famous actor played _____ important role in_____ movie Beautiful life. A. a; the B. an; / C. an; the D. a; /

已知正数x,y满足=1,则xy有( )A.最小值12

答案

相关题目

最新题目