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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 the general term (the nth term) of a geometric sequence to find the indicated term of each sequence with the given first term, a1 and common ratio, r. Find a8 when a1 = 6, r = 2

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Recall the formula for the nth term of a geometric sequence: \(a_n = a_1 \times r^{n-1}\), where \(a_1\) is the first term, \(r\) is the common ratio, and \(n\) is the term number.
Identify the given values: the first term \(a_1 = 6\), the common ratio \(r = 2\), and the term to find is the 8th term, so \(n = 8\).
Substitute the known values into the formula: \(a_8 = 6 \times 2^{8-1}\).
Simplify the exponent: \(8 - 1 = 7\), so the expression becomes \(a_8 = 6 \times 2^7\).
Evaluate \$2^7$ (which is \(2\) multiplied by itself 7 times) and then multiply the result by 6 to find $a_8$.

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Geometric Sequence

A geometric sequence is a list of numbers where each term after the first is found by multiplying the previous term by a constant called the common ratio. For example, if the first term is 6 and the ratio is 2, the sequence is 6, 12, 24, and so on.
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General Term Formula of a Geometric Sequence

The nth term of a geometric sequence can be found using the formula a_n = a_1 * r^(n-1), where a_1 is the first term, r is the common ratio, and n is the term number. This formula allows direct calculation of any term without listing all previous terms.
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Exponentiation in Sequences

Exponentiation is used in the general term formula to raise the common ratio to the power of (n-1). Understanding how to compute powers is essential to correctly find terms in geometric sequences, such as calculating 2^(7) when finding the 8th term.
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