Question

simplify 9c4combinations

Answer 1

EXPLANATION:

Given;

We are given the following information;

$_9C_4$

Required;

We are required to simplify the expression;

"Number of combinations of 9 things taken 4 at a time."

Step-by-step solution;

The formula for solving combinations is;

$_nC_r=\frac{n!}{(n-r)!\times r!}$

We can now substitute the given values and solve;

$_9C_4=\frac{9!}{(9-4)!\times4!}$$_=\frac{9\times8\times7\times...1}{(5\times4\times3\times...1)\times4\times3\times2\times1}$$=\frac{362880}{120\times24}$$=\frac{362880}{2880}$$=126$

Therefore;

ANSWER:

$_9C_4=126$