6 marksThe Binomial Theorem
CAPE Pure Mathematics Unit 2 · May/June 2014 · Paper 2 · Question 4(b)
Show that \frac{n!}{(n - r)!r!} + \frac{n!}{(n - r + 1)!(r - 1)!} = \frac{(n + 1)!}{(n - r + 1)!r!}.
The mark scheme is shown once you've answered.
Practise this question