Use the formula for the sum of the first n terms of a geometric sequence to solve Exercises 25–30. Find the sum of the first 14 terms of the geometric sequence: - 3/2, 3, - 6, 12, ...
Ch. 8 - Sequences, Induction, and Probability

Chapter 9, Problem 28
In Exercises 23–28, evaluate each factorial expression. (2n+1)!/(2n)!
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Identify the factorial expressions in the problem: \((2n+1)!\) and \((2n)!\).
Recall the definition of a factorial: \(n! = n \times (n-1) \times (n-2) \times \ldots \times 1\).
Express \((2n+1)!\) in terms of \((2n)!\): \((2n+1)! = (2n+1) \times (2n)!\).
Substitute the expression for \((2n+1)!\) into the original problem: \(\frac{(2n+1) \times (2n)!}{(2n)!}\).
Simplify the expression by canceling out \((2n)!\) from the numerator and the denominator, leaving \(2n+1\).

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Factorial Definition
A factorial, denoted as n!, is the product of all positive integers from 1 to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. Factorials are used in permutations, combinations, and various mathematical calculations, making them fundamental in algebra and combinatorics.
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Properties of Factorials
Factorials have specific properties that simplify calculations, such as n! = n × (n-1)! and 0! = 1. These properties allow for the reduction of factorial expressions, which is essential when evaluating complex factorial ratios like (2n+1)!/(2n)!. Understanding these properties helps in manipulating and simplifying expressions effectively.
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Ratio of Factorials
The ratio of two factorials, such as (2n+1)!/(2n)!, can be simplified by canceling common terms. This involves recognizing that (2n+1)! = (2n+1) × (2n)!, allowing for the expression to reduce to (2n+1). This concept is crucial for evaluating factorial expressions efficiently and accurately.
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