OCR
Further Additional Pure
2018
September
Q5
11 marks
Hard +2.3
- You are given that \(N = \binom{p-1}{r}\), where \(p\) is a prime number and \(r\) is an integer such that \(1 \leq r \leq p - 1\).
By considering the number \(N \times r!\), prove that \(N \equiv (-1)^r \pmod{p}\). [5]
- You are given that \(M = \binom{2p}{p}\), where \(p\) is an odd prime number. Prove that \(M \equiv 2 \pmod{p}\). [6]