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Mathematics 21 Online
OpenStudy (anonymous):

log[9] 27

OpenStudy (anonymous):

is the base 9?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

I would divide up the log with the rules of logarithms.

OpenStudy (anonymous):

log 27 / log 9

OpenStudy (anonymous):

you could use this formula to simplify it: \[\log_{b^{n}}(x) = \frac{1}{n}\log_b(x)\]

OpenStudy (anonymous):

is says use the change-of-base property and a calculator is find a decimal appoximation

OpenStudy (anonymous):

joe, what's that rule called? it's been a while since i did this stuff

OpenStudy (anonymous):

so: \[\log_9(27) = \log_{3^{2}}(27) = \frac{1}{2}\log_3(27) = \frac{1}{2}\log_3(3^{3}) = \frac{1}{2}*3 = \frac{3}{2}\]

OpenStudy (anonymous):

i dont know what the rule is called to be honest, i just made it up based on what you said: \[\log_9(27) = \frac{\log(27)}{\log(9)} = \frac{\log(27)}{2\log(3)} = \frac{1}{2}*\frac{\log(27)}{\log(3)} = \frac{1}{2}\log_3(27)\]

OpenStudy (anonymous):

so its 3/2

OpenStudy (anonymous):

yes :)

OpenStudy (anonymous):

also like how 9^3/2 is the square root of 9^3 = 27

OpenStudy (anonymous):

oh yeah, that works too, i wish i had seen it that way o.O

OpenStudy (anonymous):

Ahh, cool! Thanks you guys, you rock my socks off!

OpenStudy (anonymous):

it would become: \[\log_9(27) = \log_9(9^{\frac{3}{2}}) = \frac{3}{2}\] much shorter :)

OpenStudy (anonymous):

yupp

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