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Ch. 8 - Sequences, Induction, and Probability
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
All textbooksBlitzer 8th EditionCh. 8 - Sequences, Induction, and ProbabilityProblem 25
Chapter 9, Problem 25

Evaluate each expression.
7C35C4−98!96!\(\frac{_7C_3}{_5C_4}\) - \(\frac{98!}{96!}\)

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1
Identify the combinations in the expression: \$7C3\( and \)5C4$. Recall that the combination formula is given by \(nCr = \frac{n!}{r!(n-r)!}\).
Write out each combination using the formula: \(7C3 = \frac{7!}{3!(7-3)!} = \frac{7!}{3!4!}\) and \(5C4 = \frac{5!}{4!(5-4)!} = \frac{5!}{4!1!}\).
Calculate each combination separately by simplifying the factorial expressions. For example, simplify \$7!\(, \)3!\(, and \)4!\( as needed to find \)7C3\(, and similarly for \)5C4$.
Evaluate the factorial fraction \(\frac{98!}{96!}\) by simplifying it. Remember that \(\frac{98!}{96!} = 98 \times 97\) because the factorial terms cancel out except for the last two factors.
Substitute the values of \$7C3\(, \)5C4$, and \(\frac{98!}{96!}\) back into the original expression and perform the subtraction to complete the evaluation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Combination Formula

A combination represents the number of ways to choose a subset of items from a larger set without regard to order. It is calculated using the formula nCr = n! / [r!(n-r)!], where n is the total number of items and r is the number chosen.
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Factorials

A factorial, denoted by n!, is the product of all positive integers from 1 up to n. Factorials are fundamental in permutations and combinations, simplifying expressions involving counting and arrangements.
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Simplifying Factorial Expressions

When evaluating expressions involving factorials, it is often helpful to cancel common terms in the numerator and denominator. This simplification reduces computational complexity and helps in accurately calculating combinations or other factorial-based expressions.
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