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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
Chapter 9, Problem 41

Find the sum of the first 60 positive even integers.

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1
Recognize that the first 60 positive even integers form an arithmetic sequence where the first term \(a_1\) is 2 and the common difference \(d\) is also 2.
Use the formula for the \(n\)-th term of an arithmetic sequence: \(a_n = a_1 + (n-1)d\). Here, calculate the 60th term \(a_{60}\) as \(2 + (60-1) \times 2\).
Recall the formula for the sum of the first \(n\) terms of an arithmetic sequence: \(S_n = \frac{n}{2} (a_1 + a_n)\).
Substitute \(n=60\), \(a_1=2\), and the value of \(a_{60}\) from step 2 into the sum formula to set up the expression for the sum.
Simplify the expression to find the sum of the first 60 positive even integers.

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Key Concepts

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

Even Integers

Even integers are whole numbers divisible by 2 without a remainder. The first positive even integers start from 2 and increase by 2 each time (2, 4, 6, ...). Understanding this sequence helps identify the terms involved in the problem.
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Arithmetic Sequence

An arithmetic sequence is a list of numbers with a constant difference between consecutive terms. Here, the even integers form an arithmetic sequence with a common difference of 2. Recognizing this allows the use of formulas to find sums efficiently.
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Sum of an Arithmetic Series

The sum of the first n terms of an arithmetic sequence can be found using the formula S_n = n/2 * (first term + last term). This formula simplifies calculating the total of many terms without adding each individually.
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