# Need help with logs

• Dec 12th 2011, 11:22 AM
MagisterPS3
Need help with logs
Write log p / square root of q in terms of log p and log q.

Solve the equation - 4 ^(3x + 1) = 7

Thanks
• Dec 12th 2011, 11:25 AM
MagisterPS3
Re: Need help with logs
That isnt a minus 4
• Dec 12th 2011, 11:29 AM
emakarov
Re: Need help with logs
Quote:

Originally Posted by MagisterPS3
Write log p / square root of q in terms of log p and log q.

I am assuming it's $\log(p/\sqrt{q})$, not $(\log p)/\sqrt{q}$. In plain text, one could write log(p) / sqrt(q). Have you tried applying different logarithm identities?

Quote:

Originally Posted by MagisterPS3
Solve the equation - 4 ^(3x + 1) = 7

Have you seen examples of solutions of such equations?
• Dec 12th 2011, 11:38 AM
MagisterPS3
Re: Need help with logs
I have seen examples of both but im not sure how to put in terms of a letter...
• Dec 12th 2011, 11:44 AM
Plato
Re: Need help with logs
Quote:

Originally Posted by MagisterPS3
I have seen examples of both but im not sure how to put in terms of a letter...

Here is an example to follow:
$\log(a^2\sqrt[3]b)=2\log(a)+\tfrac{1}{3}\log(b).$

We add logs for multiplication, what is done for division?
• Dec 12th 2011, 11:45 AM
emakarov
Re: Need help with logs
For the first problem, try applying some of the four identities in the link from post #3. For the second problem, multiply both sides by -1, apply $\log_4$ to both sides and use the fact that $\log_4\left(4^y\right)=y$.
• Dec 12th 2011, 11:51 AM
MagisterPS3
Re: Need help with logs
Thanks very much guys I got it. :)