Question

Evaluate 7C3 explain how you got your answer

Answer 1

Formula is

ₙCₖ = (n!)/( k!*(n-k)! )

so ₇C₃ = (7!) / (3! * (7-3)!)

and 7! = 7 * 6 * 5 * 4 * 3 * 2 * 1

= (7 * 6 * 5 * 4 * 3 * 2 * 1)/(3 * 2 * 1 * 4!)
= (7 * 6 * 5 * 4)/(4!)
= (7 * 6 * 5 * 4)/(4 * 3 * 2 * 1)
= (7 * 6 * 5 )/(6 * 1)
= (7 * 5 )/( 1)
= 35