Properties of logarithmic functions  TOPIC_SOLVED

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Properties of logarithmic functions

Postby crescentcitycid on Sun Feb 27, 2011 9:32 pm

I have a series of problems that state: given that logb(2)=.39, logb(3)=.61 and logb(5)=.9, find the following for logs, do no try to find "b"

Then there are easy ones to solve using multiplication and division properties, but there is one I'm not sure about.

blogb(5)

Can that go any further than b.9 ?
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Postby stapel_eliz on Sun Feb 27, 2011 10:10 pm

crescentcitycid wrote:...there is one I'm not sure about.

blogb(5)

Can that go any further than b.9 ?

Yes. In fact, avoid that entirely. Instead of simplifying the exponent on , try setting up and solving an exponential equation:

. . . . .

...for some numerical value Then:

. . . . .

Apply a log rule to get:

. . . . .

Simplify the left-hand side, and the answer should pop out at you. :wink:
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Re: Properties of logarithmic functions

Postby crescentcitycid on Sun Feb 27, 2011 10:18 pm

.9
Awesome, thank you.
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Postby stapel_eliz on Sun Feb 27, 2011 10:37 pm

crescentcitycid wrote:.9

No. Try simplifying the left-hand side. Then look at what you have left.
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Re: Properties of logarithmic functions

Postby crescentcitycid on Sun Feb 27, 2011 10:51 pm

Well if logb(5)=.9 and logbb=1 then .9(1)=.9
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  TOPIC_SOLVED

Postby stapel_eliz on Mon Feb 28, 2011 12:48 am

Start with the equation I gave you earlier. Follow the instructions.

What is the expression for the right-hand side? What is the simplified (not "evaluated") form of the left-hand side?
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