I am not sure where to start with this problem.
If n is a positive integer and n > 1, prove that C(n, 2) + C(n-1, 2) is a perfect square.
Any hints would be appreciated.
Even after trying to plug the equation I still am unsure how to set up the proof.
C(n, r) = n! / r!(n-r)!
shouldn't the bases of both equations be 2!(n-2)!