Lôgarit

N

nguyenbahiep1

[laTEX]log_{\frac{x}{2}}x^2 - 14log_{16}x^3 + 40log_{4x}\sqrt{x} = 0 \\ \\ TXD: x > 0 , x \not = 2 , \frac{1}{4} \\ \\ \frac{2log_2x}{log_2x-1} - \frac{21log_2x}{2}+\frac{20log_2x}{2+log_2x} = 0 \\ \\ log_2x = t \\ \\ \Rightarrow \frac{2t}{t-1} - \frac{21t}{2}+\frac{20t}{2+t} = 0 \Rightarrow t = 0 , t = - \frac{1}{3} , t = \frac{10}{7}[/laTEX]
 
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