[Toán 12] Bất phương trình mũ - logarit

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vietphuonga1

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hn3

[TEX]3^{2-x}+6.3^{1-x}>\frac{1}{3}^{\sqrt{x^2+x-2}-3}(1)[/TEX]

Ta có :

[TEX](1)<=>3^2.3^{-x}+6.3.3^{-x}>3^{3-\sqrt{(x-1)(x+2)}}[/TEX]

[TEX]<=>27.3^{-x}>3^3.3^{-\sqrt{(x-1)(x+2)}[/TEX]

[TEX]<=> 3^{-x}>3^{-\sqrt{(x-1)(x+2)}}[/TEX]

[TEX]==>3^{\sqrt{(x-1)(x+2)}}>3^x[/TEX]

Dễ rồi =))
 
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