I dont remember how to do this problem and being summer, I dont have my textbook to help.

Solve: 4^(x+2)=9^(x-1)

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- Aug 26th 2008, 01:57 PMceasar_19134Need help with exponents
I dont remember how to do this problem and being summer, I dont have my textbook to help.

Solve: 4^(x+2)=9^(x-1) - Aug 26th 2008, 02:01 PMMoo
- Aug 26th 2008, 02:09 PMceasar_19134
I still cant figure it out, sorry. All of the other problems I have to do have the same base or can be simplified to have the same base.

- Aug 26th 2008, 02:22 PMMoo
Whatever base you choose, the rules are the same :)

denotes the natural logarithm and is like an *universal* base :

Continuing from :

Group the x together :

Now, if you take the logarithm in base 2, you'll have because . Actually, it's .

But in a common logarithm, you have :

, same goes for

Substituting in (1) :

Simplify by 2 :

You gotta learn how to use the natural logarithm. Using bases just sometimes avoid difficulties things easier, but in exercises like this one, it brings difficulties ! - Aug 30th 2008, 06:07 AMShowcase_22
I did it a different way:

http://i116.photobucket.com/albums/o...hsproblem2.jpg