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Mathematics 23 Online
OpenStudy (anonymous):

write as a single logarithm...

OpenStudy (anonymous):

\[\log_{3}\sqrt{x} -\log_{3}x^{6}\]

OpenStudy (anonymous):

the subscript under log is 3

OpenStudy (anonymous):

Hello Laurenn ^.^ \[\huge \log_bM - \log_bN = \log_b\frac{M}N\]

OpenStudy (anonymous):

i get that, i just don't know where to go from there

OpenStudy (anonymous):

Well, why not do it directly? :) \[\huge = \log_3\frac{\sqrt x}{x^6}\]

OpenStudy (anonymous):

But remember \[\huge \sqrt x = x^{\frac12}\]

OpenStudy (anonymous):

so would it be \[-1/2\log_{3}x \] ?

OpenStudy (anonymous):

Write as a single log first, and then simplify like that... start with this \(\huge =\log_3\frac{\sqrt x}{x^6}\)

OpenStudy (anonymous):

how would you simplify that though?

OpenStudy (anonymous):

hmm... I guess, you could do this...\[\huge =\log_3\frac{x^{\frac12}}{x^6}\] and use laws of exponents to express both with just one exponent :)

OpenStudy (anonymous):

x^3?

OpenStudy (anonymous):

no... \[\huge =\log_3 x^{\frac12-6}\]

OpenStudy (anonymous):

so -5 and a half?

OpenStudy (anonymous):

Yup :) \[\huge = \log_3x^{-\frac{11}2}\]now simplify the way you did :)

OpenStudy (anonymous):

yes i got it! -11/2log3x thank you :)

OpenStudy (anonymous):

can you help me with other logarithmic equations?

OpenStudy (anonymous):

Sure :)

OpenStudy (anonymous):

\[2\log_{5}(x-9)+\log_{5}5=3 \]

OpenStudy (anonymous):

ohh... solving :) Here's another property of logs :) \[\huge \log_bM + \log_b N = \log_bMN\]

OpenStudy (anonymous):

But first... \[\huge 2\log_5(x-9)=\log_b(x-9)^2\]

OpenStudy (anonymous):

and then what?

OpenStudy (anonymous):

Well, use the property I posted (the log M + log N = log MN)

OpenStudy (anonymous):

So... \[\Large \log_5(x-9)^2 + \log_5 5 = 3\]

OpenStudy (anonymous):

Or, actually, you can just remember that \[\huge \log_bb = 1\]

OpenStudy (anonymous):

so log5(x-9)^2+1=3 ?

OpenStudy (anonymous):

Yup :) Now bring everything with no log to the right side ^.^

OpenStudy (anonymous):

so 2=log5(x-9)^2 ... would i expand x-9^2 or just leave it like that?

OpenStudy (anonymous):

Nah, leave it like that :D \[\huge \log_bM = x \rightarrow b^x = M\]

OpenStudy (anonymous):

So... \[\huge \log_5(x-9)^2 = 2\]\[\huge (x-9)^2=5^2\] Don't bother simplifying, just take the square root of both sides ^_^

OpenStudy (anonymous):

wait so x-9=square root of 5?

OpenStudy (anonymous):

@PeterPan

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