any idea how I can simplify this

[paper axle]

How do I simplify this

[chilly sage]

what have you tried so far

[paper axle]

taking n out or trying to create general term of a binomial expansion

I got this but it doesn't really help much

@chilly sage

[chilly sage]

i would suggest to cancel what you know

the (n-2)! in the bottom and n! in the top

[paper axle]

it's not n-2 in bottom it's n - r

@chilly sage

[chilly sage]

you have 2 unknowns in the bottom?

[paper axle]

uh yes basically we have (n-r)(r-2)

in bottom