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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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#1 2013-07-05 14:05:57

{7/3}
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logarithm

prove that if r is real,then log r is real.


There are 10 kinds of people in the world,people who understand binary and people who don't.

#2 2013-07-05 17:09:32

bob bundy
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Re: logarithm

{7/3} wrote:

prove that if r is real,then log r is real.

hhmmm.  That's going to be tough when r is a negative real number.

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

#3 2013-07-05 18:43:54

{7/3}
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Re: logarithm

sorry forgot to say positive


There are 10 kinds of people in the world,people who understand binary and people who don't.

#4 2013-07-05 20:19:00

bob bundy
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Re: logarithm

This time, I think it is down to the definition:

http://en.wikipedia.org/wiki/Logarithm

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

#5 2013-07-05 22:09:28

{7/3}
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Re: logarithm

I want a proof that b for every positive b and n there is a real number x such that b^x=n


There are 10 kinds of people in the world,people who understand binary and people who don't.

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