SOLUTION: Evaluate the given expression: C(n,n-2)

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Question 919004: Evaluate the given expression:
C(n,n-2)
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Use 

1.  The identity C(A,B) = C(A,A-B)

and

2. C(A,B) = 

C(n,n-2) = C(n,n-(n-2)) = C(n,n-n+2) = C(n,2) = n%28n-1%29%2F2%21 = n%28n-1%29%2F2

Edwin