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## #1 2013-07-04 16:05:57

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### 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.

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## #2 2013-07-04 19:09:32

bob bundy
Registered: 2010-06-20
Posts: 8,322

### 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

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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## #3 2013-07-04 20:43:54

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### 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.

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## #4 2013-07-04 22:19:00

bob bundy
Registered: 2010-06-20
Posts: 8,322

### Re: logarithm

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

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

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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## #5 2013-07-05 00:09:28

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### 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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