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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 13

Use the formula for nCr to evaluate each expression. 7C7

Guida verificata passo dopo passo
1
Recall the formula for combinations, which is given by \(nCr = \frac{n!}{r!(n-r)!}\), where \(n!\) denotes the factorial of \(n\).
Identify the values of \(n\) and \(r\) from the expression \(\binom{7}{7}\), so here \(n = 7\) and \(r = 7\).
Substitute these values into the formula: \(\binom{7}{7} = \frac{7!}{7!(7-7)!}\).
Simplify the factorial in the denominator: \(7 - 7 = 0\), so the expression becomes \(\frac{7!}{7! \times 0!}\).
Recall that \$0!$ is defined as 1, so the expression simplifies to \(\frac{7!}{7! \times 1}\), which can be further simplified by canceling \$7!$ in numerator and denominator.

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Combination Formula (nCr)

The combination formula 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 fundamental for solving problems involving selections or subsets.
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Combinations

Factorial Function

The factorial of a non-negative integer n, denoted n!, is the product of all positive integers from 1 to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. Factorials are essential in the combination formula to calculate permutations and combinations.
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Factorials

Special Case: nCr when r = n

When the number of items chosen r equals the total number n, the combination nCr equals 1 because there is exactly one way to choose all items from the set. This simplifies calculations and helps quickly evaluate expressions like 7C7.
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Geometric Sequences - Recursive Formula