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Question-194613




Question Number 194613 by cortano12 last updated on 11/Jul/23
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Answered by MM42 last updated on 11/Jul/23
(1/(log_x 4x))+(1/(log_x (x/2)))=2  (1/(2log_x 2+1))+(1/(1−log_x 2))=2  let  log_x 2=y  4y^2 −y=0⇒y=0=log_x 2  ×  or  y=(1/4)=log_x 2⇒x=16 ✓
$$\frac{\mathrm{1}}{{log}_{{x}} \mathrm{4}{x}}+\frac{\mathrm{1}}{{log}_{{x}} \frac{{x}}{\mathrm{2}}}=\mathrm{2} \\ $$$$\frac{\mathrm{1}}{\mathrm{2}{log}_{{x}} \mathrm{2}+\mathrm{1}}+\frac{\mathrm{1}}{\mathrm{1}−{log}_{{x}} \mathrm{2}}=\mathrm{2} \\ $$$${let}\:\:{log}_{{x}} \mathrm{2}={y} \\ $$$$\mathrm{4}{y}^{\mathrm{2}} −{y}=\mathrm{0}\Rightarrow{y}=\mathrm{0}={log}_{{x}} \mathrm{2}\:\:× \\ $$$${or}\:\:{y}=\frac{\mathrm{1}}{\mathrm{4}}={log}_{{x}} \mathrm{2}\Rightarrow{x}=\mathrm{16}\:\checkmark \\ $$$$ \\ $$
Answered by mahdipoor last updated on 11/Jul/23
log_(ab) c=(1/(log_c ab))=(1/(log_c a+log_c b))  log_(4x) x+log_(x/2) x=(1/(log_x 4+log_x x))+(1/(log_x x+log_x 1/2))=  =(1/(2log_x 2+1))+(1/(1−log_x 2))=2⇒log_x 2=u≠1,−.5⇒  (1−u)+(2u+1)=2(1−u)(2u+1)⇒  log_x 2=(1/(log_2 x))=(1/4),0⇒x=2^4 =16
$${log}_{{ab}} {c}=\frac{\mathrm{1}}{{log}_{{c}} {ab}}=\frac{\mathrm{1}}{{log}_{{c}} {a}+{log}_{{c}} {b}} \\ $$$${log}_{\mathrm{4}{x}} {x}+{log}_{{x}/\mathrm{2}} {x}=\frac{\mathrm{1}}{{log}_{{x}} \mathrm{4}+{log}_{{x}} {x}}+\frac{\mathrm{1}}{{log}_{{x}} {x}+{log}_{{x}} \mathrm{1}/\mathrm{2}}= \\ $$$$=\frac{\mathrm{1}}{\mathrm{2}{log}_{{x}} \mathrm{2}+\mathrm{1}}+\frac{\mathrm{1}}{\mathrm{1}−{log}_{{x}} \mathrm{2}}=\mathrm{2}\Rightarrow{log}_{{x}} \mathrm{2}={u}\neq\mathrm{1},−.\mathrm{5}\Rightarrow \\ $$$$\left(\mathrm{1}−{u}\right)+\left(\mathrm{2}{u}+\mathrm{1}\right)=\mathrm{2}\left(\mathrm{1}−{u}\right)\left(\mathrm{2}{u}+\mathrm{1}\right)\Rightarrow \\ $$$${log}_{{x}} \mathrm{2}=\frac{\mathrm{1}}{{log}_{\mathrm{2}} {x}}=\frac{\mathrm{1}}{\mathrm{4}},\mathrm{0}\Rightarrow{x}=\mathrm{2}^{\mathrm{4}} =\mathrm{16} \\ $$

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