How do I solve a logarithmic equation?
For example, log2 (x+4) + log2 (x) = 5.

Question

How do I solve a logarithmic equation?
For example, log2 (x+4) + log2 (x) = 5.

anonymous · Answer

is that log base 2 ???

anonymous · Answer

or log base 10 ???

nory · Answer

Yes. I haven't gotten the hang of the controls yet.

anonymous · Answer

???

anonymous · Answer

i will bet base 2

anonymous · Answer

is this the problem:  $\large log_2(x+4)+log_2(x)=5 $

or is it:   $\large log2(x+4)+log2(x)=5 $

nory · Answer

It is the former.

anonymous · Answer

@satellite73 ... ding, ding, ding, ding!!!

anonymous · Answer

ok... do you know this rule for logs:  $\large log_bM+log_bN=log_b(M\cdot N) $  ???

nory · Answer

Yes, I do. So I use that rule and then what do I do?
I think I know the answer but I could use a refresher.

anonymous · Answer

so you can apply that to the left side of the equation to get :
$\huge log_2[x(x+4)]=5 $

we good so far?

nory · Answer

Yes. I understand. So then I expand x(x+4)?

anonymous · Answer

yes... but you can do that later...

anonymous · Answer

do you know how to write this logarithmic equation in exponential form:

$\large log_{10}(1000)=3 $  ???

nory · Answer

10 ^ 3 = 1000. Yes. So I write the equation in exponential form?

anonymous · Answer

yes.... :)

anonymous · Answer

wat equation u got now?