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## #1 2012-12-03 23:55:15

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### Solving for x

I am solving for X below:

4^(3x+5) = 1/256

The answer I get is -3 please correct me if I am wrong and why if you can please. Much appreciated.

## #2 2012-12-03 23:58:52

bob bundy
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### Re: Solving for x

Welcome to the forum.

That answer looks good to me.

Bob

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

## #3 2012-12-04 01:15:20

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### Re: Solving for x

Sometimes I get x = -1/3 so Im not sure whats the right way to do it. :-(

## #4 2012-12-04 01:18:34

bobbym

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### Re: Solving for x

Hi;

You can convert that expression on the right to be

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #5 2012-12-04 01:23:03

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### Re: Solving for x

I'm not sure. I think I don't understand.

## #6 2012-12-04 01:26:14

bobbym

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### Re: Solving for x

You now have

Here is a trick to these types whenever the bases are the same

you can ignore them and just solve the equation that you get from the exponents.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #7 2012-12-04 04:12:01

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### Re: Solving for x

That trick makes a lot of sense, but, what about when one number cannot be the same? Like the 6 below:

3^x+7=6

## #8 2012-12-04 04:45:38

bob bundy
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### Re: Solving for x

I'd do it like this:

Unfortunately, that's where this question unravels because you'd need to go into complex number theory to sort out log(-1).

This sort of thing happens if you make up a question at random.  (And you thought it was easy for a teacher to throw some questions together)

Bob

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

## #9 2012-12-04 05:05:17

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### Re: Solving for x

Maybe if I re-write it.

3^(x+7)=6

## #10 2012-12-04 05:12:15

bob bundy
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### Re: Solving for x

OK.  That'll do.

Bob

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