Evaluate the following expression. 9C3
To evaluate 9C3, we use the combination formula:
nCr = n! / r!(n-r)!
Plugging in n = 9 and r = 3:
9C3 = 9! / 3!(9-3)!
= 9! / 3!6!
= (9x8x7x6x5x4x3x2x1) / (3x2x1)(6x5x4x3x2x1)
= (9x8x7) / 3x2
= 84
Therefore, 9C3 is equal to 84.