Chapter 12.6, Problem 21P

Find the value of each expression.

${}_9{C}_4$

To determine

Find the value of the given expression.

Answer to Problem 21P

126

Explanation of Solution

Given:

The given expression is :

  $C{}_4$

Formula Used:

  $C{}_r=\frac{n!}{r!(n-r)!}$

Calculation:

  $C{}_4=\frac{9!}{4!(9-4)!}=\frac{9!}{4!5!}=\frac{9\cdot 8\cdot 7\cdot 6\cdot 5!}{4!5!}=126$ .