logarit

X

xuanquynh97

PT \Leftrightarrow $log_{2}(9^{x-2}+7)=log_22+log_2(3^{x-2}+1)$

\Leftrightarrow $log_2(9^{x-2}+7)=log_2[4(3^{x-2}+1)]$

\Leftrightarrow $9^{x-2}+7=4(3^{x-2}+1)$

\Leftrightarrow $(3^{x-2}-1)(3^{x-2}-3)=0$

Vậy x=2 hoặc x=3
 
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