Logarithms help

[BlackWeenie]

alright i have a test on logs on monday and im having some trouble with it. someone please help me out on this one. a step by step description would help, or if you could just answer it and show your work that would be great. i realize that these are all very similar but i dont get any of them.

Key
if exponent is 4 to the power of 5, it will be written like this- 4^5
if base is 4, it will be written like this- [base=4]

1. 15^(x-1) = 9^x

2. log[base=2](log[base=5]x) = 2

3. 7^(2log[base=7]x + log[base=7]x) = 27

any help is appreciated

[BlackWeenie]

...

[845]

I forgot how to do these but i do remember they are very easy.

[Rob218]

For #3, x=3. I'll scan my work here in a second.

http://img58.exs.cx/img58/1264/LogNo3.jpg

[BlackWeenie]

wow, thanks. i cant believe how much trouble i was having on that question its so easy

[tropical_fishy]

log[base=2](log[base=5]x) = 2

-2^(log[base=2](log[base=5]x))=2^2

-log[base=5)x=4

-5^log[base=5)x=5^4

-x=5^4