Answer
$ 72$
Work Step by Step
RECALL:
$P(n, r) = \dfrac{n!}{(n-r)!}$
Use the formula above to obtain:
$P(9, 2) = \dfrac{9!}{(9-2)!}
\\P(9, 2) = \dfrac{9!}{7!}
\\P(9, 2) = \dfrac{9(8)(7!)}{7!}$
Cancel the common factor $7!$ to obtain:
$P(9, 2) = 9(8)
\\P(9, 2) = 72$
