# Exponent laws

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1. Jan 28, 2016

### PhysicsBoyMan

1. The problem statement, all variables and given/known data
x(cnxn-1)

3. The attempt at a solution

I know that the answer is cnxn

I'm not sure why though. My thinking is that we have cnxn-1 and we multiply that by x. x times x is x2 so I'm expecting a 2 to interact with the n-1 in the exponents. I'm just not sure how n-1 interacts with 2 to produce n.

I don't add n-1 + 2 to get n + 1 because I already have the answer and its not that. I just can't see how I would get from n-1 to n by interacting with a 2.

Thanks for the help.

2. Jan 28, 2016

### SammyS

Staff Emeritus
You may know the answer to the question.

We're not any good at guessing just what that question might be.

What is the question?

3. Jan 28, 2016

### PhysicsBoyMan

The question is the multiplication of x times cnxn-1

4. Jan 28, 2016

### SteamKing

Staff Emeritus
I don't know where you are getting that you are multiplying x times x here.

You are multiplying x times xn-1, which is something different.

That's what x(cnxn-1) means. It can also be written as c ⋅ n ⋅ x ⋅ xn-1

5. Jan 28, 2016

### SammyS

Staff Emeritus
Oh! You want to simplify the product, x⋅cnxn-1 .

So the 'question' is:
What is the result of simplifying x⋅cnxn-1 ?
And you want to know how it is that simplifies to be cnxn .
.

6. Jan 28, 2016

### HallsofIvy

Have you never actually taken an Algebra class? If you have you should have learned one of the basic 'laws of exponents':
$(a^m)(a^n)= a^{m+n}$. Here the problem is to multiply x, which is the same as $x^1$, by $x^{n-1}$.
Mod note: Portion deleted as too much help.

Last edited by a moderator: Jan 28, 2016