Prove Theorem 2.6.7. (a) by using the Product Rule. (b) by induction on n. Use...

Prove Theorem 2.6.7.

(a) by using the Product Rule.

(b) by induction on n. Use part (c) of Theorem 2.6.9.

Theorem 2.6.7.

The Permutation Rule

If n is a natural number and r is an integer such that 0 ≤ r ≤ n. then the number of permutations of any r distinct objects from a set of n objects is

Theorem 2.6.9

Let n be a positive integer and r be an integer such that 0 ≤ r ≤ n.