# Thread: Change of Base Formula Logarithms

1. ## Change of Base Formula Logarithms

I know how to use the change of base for logarithm problems but how do you so it for natural logs? The question reads "Write the logarithm as a multiple of common logarithm". None of the examples are for natural logs. How would I solve. "ln 5" using this?

2. Originally Posted by whiteforlife
I know how to use the change of base for logarithm problems but how do you so it for natural logs? The question reads "Write the logarithm as a multiple of common logarithm". None of the examples are for natural logs. How would I solve. "ln 5" using this?
I'm not exactly sure what you mean, but I think the question asks you to transform $\ln 5$ into a normal logarithm form.

$\ln x = \frac {\log_{10}x}{\log_{10}e}$

I really ain't sure, please be more specific.

3. Originally Posted by whiteforlife
I know how to use the change of base for logarithm problems but how do you so it for natural logs? The question reads "Write the logarithm as a multiple of common logarithm". None of the examples are for natural logs. How would I solve. "ln 5" using this?
Natural logarithm is just a logarithm with a base e.

$\ln x = \log_e x$

so $\ln 5 = \log_e 5$

Does this help?

Edit: Ooh, Sodapop beat me to it.