题干

知识背景,当a>0且x>0时,因为 (x
a
x
)
2
0
,所以 x2a+
a
x
0
,从而 x+
a
x
2a

(当x= a 时取等号).

设函数y=x+

a
x
(a>0,x>0),由上述结论可知:当x= a 时,该函数有最小值为2 a

应用举例

已知函数为y1=x(x>0)与函数 y2=

4
x
(x>0),则当x= 4 =2时,y1+y2=x+
4
x
有最小值为2 4 =4.

解决问题

上一题 下一题 0.0难度 选择题 更新时间:2019-11-07 01:09:44

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