Forgot password?
 Register account
View 1669|Reply 1

[函数] 请教:一道最小值问题

[Copy link]

209

Threads

950

Posts

6222

Credits

Credits
6222

Show all posts

敬畏数学 Posted 2016-11-27 21:24 |Read mode
若x,y均为正实数,且x+y=1,求1/x^2+8/y^2的最小值-----?

413

Threads

1431

Posts

110K

Credits

Credits
11099

Show all posts

realnumber Posted 2016-11-27 21:32
Last edited by realnumber 2016-11-27 21:47看到严文兰老师用赫尔德不等式解过
baike.baidu.com/link?url=W6xX4n4RFjTXSaUaaGi6 … t9PAthhe5TODTFRagkTK

\[(\frac{1}{x^2}+\frac{8}{y^2})^{\frac{1}{3}}(x+y)^{\frac{2}{3}}\ge 3\]
\[当且仅当x=\frac{1}{3},y=\frac{2}{3}\]

Mobile version|Discuz Math Forum

2025-5-31 10:33 GMT+8

Powered by Discuz!

× Quick Reply To Top Edit