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Mathematics 15 Online
OpenStudy (anonymous):

Solve each equation . CLICK !

OpenStudy (whpalmer4):

I clicked, but no equations appeared.

OpenStudy (anonymous):

oh sorry. give me 30 secs.

OpenStudy (anonymous):

\[\log _{x}32=-5\]

OpenStudy (anonymous):

@whpalmer4

OpenStudy (whpalmer4):

Okay, the log base x of 32 is the number that x needs to be raised to to give you 32.

OpenStudy (anonymous):

okay ? @whpalmer4

OpenStudy (whpalmer4):

Nuts, lost the response I was writing :-( If the log base x of 32 = -5, that means that \(x^{-5} = 32\)

OpenStudy (whpalmer4):

And by the properties of exponents, \[x^{-5} = \frac{1}{x^5}\] we could solve this by figuring out which number raised to the 5th power = 32, then take its reciprocal. What is the value of a if a*a*a*a*a = 32? 1/a will be our answer.

OpenStudy (anonymous):

sorry for the delay. but 2^5=32?

OpenStudy (anonymous):

1/2 is the answer?

OpenStudy (whpalmer4):

Yes. 1/2*1/2*1/2*1/2*1/2 = 1/32

OpenStudy (anonymous):

can you help me with the next one?

OpenStudy (whpalmer4):

And by the change of base formula, \[\log_b a = \frac{\log b}{\log a} = -5 = \frac{\log 32}{\log x}\]\[-5 \log x = \log 32\]\[\log x = \log 32/-5\]\[x = e^{\log 32/-5} = 1/2\]

OpenStudy (whpalmer4):

Post new questions in separate questions. Better for me, better for you.

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