# write log as an expression

• Nov 8th 2009, 03:55 PM
snypeshow
write log as an expression
I get what the question asks for, i just dont get how to do it.

Write an expression for the following, by using a sum/difference and/or a multiple:

http://img94.imageshack.us/img94/8489/259009.gif

i think i got it, but im not sure:

loga5a^4
= loga5 + logaa^4
= loga5 + 4logaa

is there a way to reduce logaa?
• Nov 8th 2009, 03:58 PM
skeeter
Quote:

Originally Posted by snypeshow
I get what the question asks for, i just dont get how to do it.

Write an expression for the following, by using a sum/difference and/or a multiple:

http://img94.imageshack.us/img94/8489/259009.gif

hints...

\$\displaystyle \log(xy) = \log(x) + \log(y)\$

and

\$\displaystyle \log_b(b^n) = \textcolor{red}{n}\$
• Nov 8th 2009, 04:06 PM
snypeshow
yeah, i used both those identities. i edited my original post right after you posted
• Nov 8th 2009, 05:27 PM
pencil09
Quote:

Originally Posted by snypeshow
I get what the question asks for, i just dont get how to do it.

Write an expression for the following, by using a sum/difference and/or a multiple:

http://img94.imageshack.us/img94/8489/259009.gif

i think i got it, but im not sure:

loga5a^4
= loga5 + logaa^4
= loga5 + 4logaa

is there a way to reduce logaa?

remember the identity, that:
logaa=1
loga1=0