Solving for x

gbrad88 · 2012-12-03 00:55:15

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.

Bob · 2012-12-03 00:58:52

hi gbrad88

Welcome to the forum.

That answer looks good to me.

Bob

gbrad88 · 2012-12-03 02:15:20

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

bobbym · 2012-12-03 02:18:34

Hi;

You can convert that expression on the right to be

does that help you?

gbrad88 · 2012-12-03 02:23:03

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

bobbym · 2012-12-03 02:26:14

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.

gbrad88 · 2012-12-03 05:12:01

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

Bob · 2012-12-03 05:45:38

hi gbrad88,

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

gbrad88 · 2012-12-03 06:05:17

Maybe if I re-write it.

3^(x+7)=6

Bob · 2012-12-03 06:12:15

OK. That'll do.

Bob

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