11-8 Factorials!!!!!!

Factorial: the product of the first n consecutive pos. integers ! factorial notation 5! 3! 7! 0! = 5 ∙ 4 ∙ 3 ∙ 2 ∙ 1 = 120 = 3 ∙ 2 ∙ 1 = 6 = 7 ∙ 6 ∙ 5 ∙ 4 ∙ 3 ∙ 2 ∙ 1 = 5040 = 1

Example 1 Faster: count down until reach # in denom You MUST know how to do this without a calculator!

Example 2 3 2 You need Parenthesis on the bottom if there’s more than 1 factorial!!!!!

Example 3 n n–1 n–2 n–3 n–4 n–5 n–6

Example 4 n+2 n+1 n n–1 n–2 n–3 n–4 n–5 n–6

Example 5--Working backwards Example 5--Working backwards! Write the expression as a ratio of factorials.

Example 6--Working backwards Example 6--Working backwards! Write the expression as a ratio of factorials.