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Ch. 8 - Sequences, Induction, and Probability
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 9, Problema 9

Use the formula for nCr to evaluate each expression. 9C5

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1
Recall the formula for combinations, which is used to find the number of ways to choose r objects from n objects without regard to order: \(nCr = \frac{n!}{r!(n-r)!}\).
Identify the values of n and r from the problem: here, \(n = 9\) and \(r = 5\).
Substitute these values into the formula: \(9C5 = \frac{9!}{5!(9-5)!} = \frac{9!}{5!4!}\).
Write out the factorial expressions explicitly or simplify by canceling common terms in the numerator and denominator to make calculations easier.
Calculate the simplified expression step-by-step to find the value of \$9C5$ (do not compute the final number here, just set up the expression).

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Combination Formula (nCr)

The combination formula, denoted as nCr, calculates the number of ways to choose r items from a set of n distinct items without regard to order. It is given by nCr = n! / [r! (n - r)!], where '!' denotes factorial. This formula is essential for solving problems involving selections or groups.
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Combinations

Factorials

A factorial, represented by n!, is the product of all positive integers from 1 up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. Factorials are used in the combination formula to calculate permutations and combinations by counting arrangements.
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Factorials

Evaluating Combinations

To evaluate a combination like 9C5, substitute n = 9 and r = 5 into the formula and simplify using factorial values. Understanding how to simplify factorial expressions and cancel common terms helps efficiently compute the result without calculating large numbers fully.
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Combinations