# Thread: Subscripts with a P?

1. ## Subscripts with a P?

I'm really sorry if this doesn't belong here. I just registered and I'm new.
I don't know if it belongs here because I haven't seen it before, so I don't know what classification of math it falls under.

The problem is, 'By how much does 6P3 exceed 6P2?

2. Originally Posted by DPooch
I'm really sorry if this doesn't belong here. I just registered and I'm new.
I don't know if it belongs here because I haven't seen it before, so I don't know what classification of math it falls under.

The problem is, 'By how much does 6P3 exceed 6P2?
$^nP_k = \frac{n!}{(n-k)!}$

Therefore

$^6P_3-^6P_2 = \frac{6!}{(6-3)!}- \frac{6!}{(6-2)!}$

Can you finish it?

3. Originally Posted by pickslides
$^nP_k = \frac{n!}{(n-k)!}$

Therefore

$^6P_3-^6P_2 = \frac{6!}{(6-3)!}- \frac{6!}{(6-2)!}$

Can you finish it?

720/6 - 720/24
= 120 - 30
= 90?

Thanks for the help.

Though, what is this called and what section should it be in?

4. Originally Posted by DPooch

Though, what is this called and what section should it be in?
It's fine where it is but more correctly could be put in "Basic Statistics and Probabilty" or even "Discrete Mathematics"

Moderator edit: Moved to Discrete Maths.