Solve for x

poplap

New member
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Mar 4, 2012
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2
log with a base of x(x)^1/5-log with a base of fracion1/9 3^x=3.i have no idea.thanks
 
Hello, poplap!

What an ugly problem . . .


\(\displaystyle \log_x(x^{\frac{1}{5}}) - \log_{\frac{1}{9}}\left(3^x\right) \:=\:3\)

Note that: .\(\displaystyle \log_x(x^{\frac{1}{5}}) \:=\:\frac{1}{5}\)

\(\displaystyle \text{Let: }\,\log_{\frac{1}{9}}(3^x) \:=\:p \quad\Rightarrow\quad \left(\dfrac{1}{9}\right)^P \:=\:3^x \quad\Rightarrow\quad \left(\dfrac{1}{3^2}\right)^P \:=\:3^x \)

. . . \(\displaystyle \left(3^{\text{-}2}\right)^P \:=\:3^x \quad\Rightarrow\quad 3^{\text{-}2P} \:=\:3^x \quad\Rightarrow\quad \text{-}2P \:=\:x \quad\Rightarrow\quad P \:=\:\text{-}\frac{x}{2}\)

Hence: .\(\displaystyle \log_{\frac{1}{9}}(3^x) \:=\:\text{-}\frac{x}{2}\)


The equation becomes: .\(\displaystyle \dfrac{1}{5} - \left(\text{-}\dfrac{x}{2}\right) \:=\:3 \)

Multiply by 10: ..\(\displaystyle 2 + 5x \:=\:30 \quad\Rightarrow\quad 5x \:=\:28\)

. . Therefore: .\(\displaystyle \boxed{x \;=\;\frac{28}{5}}\)
 
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