Question

n!/(n-n-2)! n-2!

Answer 1

\[\frac{n!}{(n-(n-2))!(n-2)!} = \frac{n!}{2!(n-2)!} \]
using the fact that n! = n*(n-1)*(n-2)! we get:
\[\frac{n(n-1)(n--2)!}{2!(n-2)!} = \frac{n(n-1)}{2!} = \frac{n(n-1)}{2}\]

Answer 2

ok, the first part, it wouldn't be \[n!\div -2!n-2!\]? Can you have a negative factorial?

Answer 3

no you cant.

Answer 4

ok, and then for the final anser, would that be written \[n!(n-1)!/2! \], or \[(n ^{2}-n)!/2!\], or the way your wrote it originally?

Answer 5

the second way you wrote it is good

Answer 6

sorry, just to confirm, so you would keep the exclamation points in the final answer like I have it the second way?

Answer 7

?

Answer 8

oh sry i didnt see those, you need to take out the exclamation marks.

Answer 9

ok thank you. Thanks for all your help.