log(12.5) is positive
log(0.8) is negative
If we add them we would expect an integer result if they had the same decimal.
Remember this rule of logs:
log(a) + log(b) = log(ab)
log(12.5) + log(0.8)
log(12.5 * 0.8)
log(10)
= 1
This is an integer result.
Because:
log(12.5) + log(0.8) = 1
The answer is yes, they have the same repeating decimal sequence.
2007-12-21 08:34:04
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answer #1
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answered by Puzzling 7
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using the log rules and the fact that:
10/0.8 = 12.5
we get:
log 12.5 = log 10/0.8 = log 10 - 0.8 = 1 - log 0.8
2007-12-21 08:38:45
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answer #2
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answered by iheart808 3
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I'm assuming that you are taking logs in base 10. Use the fact that log(a/b) = log(a) - log(b)
log(12.5) = log(100/8) = log(100) - log(8) = 2 - log(8)
log(0.8) = log(8/10) = log(8) - log(10) = log(8) - 1
Note that both terms are a combination of an integer and
log(8)
2007-12-21 08:36:15
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answer #3
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answered by Astral Walker 7
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They have the same decimal sequence because their mantissas are identical in base 10.
Log(12.5) = Log(10) + log(1.25) = 1 + log(1.25)
0.8 is the reciprocal of 1.25, so
Log(0.8) = - log(1.25)
Adding the 1 to log(1.25) does not change its decimal part.
2007-12-21 09:18:52
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answer #4
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answered by Helmut 7
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log 12.5 = log (100/8) = 2 - log8
log 0.8 = log(8/10) = log8 - 1
I don't know is there any relate to ur question
2007-12-21 08:37:34
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answer #5
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answered by tinhnghichtlmt 3
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Puzzling was right, except that the numbers a non-repeating irrationals. They go on forever without repetition.
2007-12-21 09:06:59
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answer #6
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answered by Tom V 6
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