Logarithms: solving log (base 0.4) 23

[youknowitsucka]

So how do I solve a logarithm, if the base isn't 10?

example:
log (base 0.4) 23

Any help is greatly appreciated!

 

[Deleted member 4993]

Re: Logarithms

use:

\(\displaystyle log_{a}b = \frac{log_{c}b}{log_{c}a}\)
where c can be any workable base.

in your case

a = 0.4

b = 23

c = 10

 

[youknowitsucka]

Re: Logarithms

So does it end up being..

log (23/0.4)?

 

[o_O]

Re: Logarithms

What do you mean by solving a logarithm ... You mean find a value for it using a calculator?

Mmm not quite there. As Subhotosh Khan had said:

\(\displaystyle log_{a}b = \frac{log_{c}b}{log_c{a}}\)

Try letting c = 10 (so that you have a base of 10 as you asked), and plug in the rest.

\(\displaystyle \frac{log_{c}b}{log_c{a}} \neq \log_{c}\left(\frac{b}{a}\right)\)