>
数学
>
已知函数f(x)满足2f(x)-f(
1
x
)=
3
x
2
,则f(x)的最小值是( )
A. 2
B. 2
2
C. 3
D. 4
人气:354 ℃ 时间:2019-10-18 02:33:19
解答
由2f(x)-f(
1
x
)=
3
x
2
①,得2f(
1
x
)-f(x)=3x
2
②,
联立①②解得f(x)=
x
2
+
2
x
2
,
f(x)=
x
2
+
2
x
2
≥2
x
2
•
2
x
2
=2
2
,当且仅当
x
2
=
2
x
2
,即x=
±
4
2
时取等号,
故f(x)的最小值为2
2
.
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