help me solve: log (x + 3) - log (x - 1) = log 2

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
milynx
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help me solve: log (x + 3) - log (x - 1) = log 2

Postby milynx » Mon Jul 27, 2009 10:04 pm

please help me solve this logaritm. Log (x + 3) - log (x - 1) = log 2

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stapel_eliz
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Postby stapel_eliz » Mon Jul 27, 2009 11:25 pm

milynx wrote:Log (x + 3) - log (x - 1) = log 2

To start in solving this log equation, first apply a log rule to convert the left-hand side to one log containing a rational expression.

. . . . .

At which point, you have "log(something) = log(2)". Set "something" equal to 2, and solve the resulting rational equation. :wink:

milynx
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Re: help me solve: log (x + 3) - log (x - 1) = log 2

Postby milynx » Mon Jul 27, 2009 11:32 pm

thank you. I ended up with x = 5. hope this is correct. thanks again!

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stapel_eliz
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Postby stapel_eliz » Tue Jul 28, 2009 12:03 am

You can check the answer to any "solving" exercise by plugging it back into the original problem. In your case:

. . . . .

Since your solution "checks", it must be correct! :D


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