# Help me with log. tmr exam!

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• March 25th 2009, 12:15 AM
helloying
Help me with log. tmr exam!
lgx+ln2x=3
solve the eqn
thanks
• March 25th 2009, 03:54 AM
Grandad
Logs
Hello helloying
Quote:

Originally Posted by helloying
lgx+ln2x=3
solve the eqn
thanks

I assume that lgx means $\log_{10}x$ and ln2x means $\log_e2x (= \log_e2 + \log_ex)$.

In which case, you need to know that $\log_{10}x = \frac{\log_ex}{\log_e10}$. So the equation becomes:

$\frac{\log_ex}{\log_e10} + \log_e2 + \log_ex = 3$

$\Rightarrow \log_ex\left(\frac{1}{\log_e10} + 1\right)= 3 - \log_e2$

Can you finish it from here?

Grandad