condensing a log

pinkcalculator

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Oct 13, 2009
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I know that subtraction becomes division, but I'm not sure how this would work out because it's divided twice.

3logx-logy-5logz

(logx cubed/log y)/logz to the fifth power??
 
3logx-logy-5logz

(logx cubed/log y)/logz to the fifth power??

Here’s an easy way to check your answer: simply pick some values for x, y, and z – say 2, 3, and 5. Plug these into the original form and note the answer. Next, plug them into your condensed form to see if you get the same answer.

If you perform this test, you’ll find that your answer is not correct. This suggests we should re-examine the “log rule” we are trying to apply.

If we were expanding the expression log(ab), we’d write

log(ab) = log(a) + log(b)

If we’re condensing, then

log(a) + log(b) = log(ab)

Similarly,

log(a) - log(b) = log(a/b)… NOT log(a)/log(b)!

With these tips in mind, give your problem another try.
 
If they share a log in condensed form, is this right??

log (x cubed divived by y) divided by z to the fifth?
 
If they share a log in condensed form, is this right??

log (x cubed divived by y) divided by z to the fifth?

Please run the check I recommended above: "simply pick some values for x, y, and z – say 2, 3, and 5. Plug these into the original form and note the answer. Next, plug them into your condensed form to see if you get the same answer."

Please show your work along with the answers you got.

Also, visit:
http://www.purplemath.com/modules/logrules.htm
(I think you're going to like it!)

I will then show you the solution then, if necessary.
 
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