Discrete Mathematics and Its Applications, Seventh Edition

Published by McGraw-Hill Education
ISBN 10: 0073383090
ISBN 13: 978-0-07338-309-5

Chapter 1 - Section 1.8 - Proof Methods and Strategy - Exercises - Page 108: 8

Answer

See explanation below.

Work Step by Step

1. Assume n is a positive integer that equals the sum of the positive integers not exceeding it. n = n + (n-1) + (n-2) + (n-3) + ... + 2 + 1 2. Summation formula n = n(n+1)/2 3. Simplify 2n = n^2 + n 0 = n^2 - n 0 = n(n - 1) Therefore, n = 0 or n = 1 The only positive integer that equals the sum of the integers not exceeding it is n = 1
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