Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**gbrad88****Member**- Registered: 2012-12-03
- Posts: 16

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.

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,868

hi gbrad88

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

Offline

**gbrad88****Member**- Registered: 2012-12-03
- Posts: 16

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

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 93,736

Hi;

You can convert that expression on the right to be

does that help you?

**In mathematics, you don't understand things. You just get used to them.**

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

Offline

**gbrad88****Member**- Registered: 2012-12-03
- Posts: 16

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

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 93,736

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 agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

Offline

**gbrad88****Member**- Registered: 2012-12-03
- Posts: 16

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

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,868

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

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

Offline

**gbrad88****Member**- Registered: 2012-12-03
- Posts: 16

Maybe if I re-write it.

3^(x+7)=6

Offline

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,868

OK. That'll do.

Bob

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

Offline

Pages: **1**