Binomial Theorem And Its Simple Applications Question 101

Question: p is a prime number and n<p<2n. if N= $ ^{2n}C_{n} $ , then

Options:

A) p divides N

B) $ p^{2} $ divides N

C) p cannot divide N

D) none of these

Show Answer

Answer:

Correct Answer: A

Solution:

  • [a] $ N{{=}^{2n}}C_{n}=\frac{(2n)!}{{{(n!)}^{2}}}=\frac{(n+1)(n+2)…(n+n)}{(n!)} $

$ \Rightarrow (n!)N=(n+1)(n+2)…(n+n) $ Since $ n<p<2n, $ so p divides (n+1)(n+2)…(n+n).