# Homework Help: How do you simplify 2n+2?

1. Nov 14, 2009

### xXOfNiRXx

Just a quick question. I'm having problems with factorials. For example, how do you simplify 2n+2!? Is it 2n!*2n+1!?

Thanks everybody!

2. Nov 14, 2009

### Staff: Mentor

Re: Factorials...

Strictly speaking, 2n + 2! would be just 2n + 2, since 2! = 2. You probably meant (2n + 2)!, which is (2n + 2)*(2n + 1)*(2n)!.

Edit: added a missing factor in the above.

Note that 2n! is different from (2n)!. The first is 2(n*(n-1)*(n-2)*...*2*1). The second is 2n*(2n-1)*(2n-2)*...*2*1.

You should get into the habit of using parentheses...

Last edited: Nov 15, 2009
3. Nov 14, 2009

### Avodyne

Re: Factorials...

Actually, it's (2n+2)*(2n+1)*(2n)!, but I'm sure you knew that.

4. Nov 15, 2009

### Staff: Mentor

Re: Factorials...

Yeah, knew that, but didn't manage to write it.
I edited my earlier post.