解不等式(2+log3 x)log3 x>log3 (9x)3都是底数

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解不等式(2+log3 x)log3 x>log3 (9x)3都是底数

解不等式(2+log3 x)log3 x>log3 (9x)3都是底数
解不等式(2+log3 x)log3 x>log3 (9x)
3都是底数

解不等式(2+log3 x)log3 x>log3 (9x)3都是底数
(2+log3 x)log3 x>log3 (9x)
=>
(2+log3 x)log3 x>log3 (9)+log3 (x)
=>
(2+log3 x)log3 x>2+log3 (x)
设log3 (x)=t
=>
(2+t)t>2+t
=>
t^2+t-2>0 t>1 or t
log3 (x)>1 or log3 (x)
x>3 or 0

03 用换元法:令t=log3x

(2+log3 x)log3 x>log3 (9x)
(2+log3 x)log3 x>log3 9+log3 x
2log3 x+(log3 x)²>2+log3 x
令t=log3 x
则上式变为:2t+t²>2+t
则t²+t-2>0
则(t+2)(t-1)>0
则t>1或t<-2
t>1时,即l...

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(2+log3 x)log3 x>log3 (9x)
(2+log3 x)log3 x>log3 9+log3 x
2log3 x+(log3 x)²>2+log3 x
令t=log3 x
则上式变为:2t+t²>2+t
则t²+t-2>0
则(t+2)(t-1)>0
则t>1或t<-2
t>1时,即log3 x>1,解得x>3
t<-2时,即log3 x<-2,解得0<x<1/9
所以原不等式的解集是:0<x<1/9或x>3

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