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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 23

Write a formula for the general term (the nth term) of each arithmetic sequence. Do not use a recursion formula. Then use the formula for an to find a20, the 20th term of the sequence. 1, 5, 9, 13,...

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1
Identify the first term of the arithmetic sequence, denoted as \(a_1\). In this sequence, the first term is \(1\).
Determine the common difference \(d\) by subtracting the first term from the second term: \(d = 5 - 1\).
Write the formula for the general term (the \(n\)th term) of an arithmetic sequence, which is \(a_n = a_1 + (n - 1) \times d\).
Substitute the values of \(a_1\) and \(d\) into the formula to get the explicit formula for this sequence.
Use the formula to find the 20th term by substituting \(n = 20\) into the general term formula.

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Arithmetic Sequence

An arithmetic sequence is a list of numbers where each term after the first is found by adding a constant difference to the previous term. For example, in the sequence 1, 5, 9, 13,... the common difference is 4. Understanding this pattern is essential to formulating the general term.
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Arithmetic Sequences - General Formula

General Term Formula of an Arithmetic Sequence

The general term (nth term) of an arithmetic sequence can be expressed as a_n = a_1 + (n - 1)d, where a_1 is the first term, d is the common difference, and n is the term number. This formula allows direct calculation of any term without listing all previous terms.
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Arithmetic Sequences - General Formula

Evaluating the nth Term

Once the general term formula is established, substituting the desired term number (like n=20) into the formula gives the specific term's value. This step avoids recursion and efficiently finds terms deep in the sequence.
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Nth Roots