Factorial Notation
Factorial Notation
\[n! = n(n-1)(n-2)\times\dots \times{3}\times 2\times 1\]
The number of ways of choosing r items from a group of n items
\(\(^{n}C_{r} =\left( \frac{n}{r} \right)=\frac{n!}{r!(n-r)!}\)\)
- \(^{n}C_{r}\) can be used to find a value in pascals triangle. This makes finding the co-efficients for binomial expansion much easier.
- The rth entry in the nth row of pascals triangle is given by \(^{n-1}C_{r-1}\)