pt logarit!!!

T

tuyn

ĐK: x > 0

[TEX]log_2(4x^2)=2(1+log_2x)[/TEX]
Đặt [TEX]t=log_2x \Rightarrow x=2^t[/TEX]

[TEX]PT \Leftrightarrow 4^t-2^{tlog_26}=2.3^{2+2t}[/TEX]

[TEX]\Leftrightarrow 4^t-6^t=18.9^t \Leftrightarrow ( \frac{2}{3})^{2t}-( \frac{2}{3})^t-18=0[/TEX]

Đến đây giải OK rồi :D
 
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