SHARE
SPREAD
HELP

The Tradition of Sharing

Help your friends and juniors by posting answers to the questions that you know. Also post questions that are not available.


To start with, Sr2Jr’s first step is to reduce the expenses related to education. To achieve this goal Sr2Jr organized the textbook’s question and answers. Sr2Jr is community based and need your support to fill the question and answers. The question and answers posted will be available free of cost to all.

 

#
Authors:
William Stallings
Chapter:
Introduction To Number Theory
Exercise:
Problems
Question:19 | ISBN:9781292158587 | Edition: 7

Question

Why is gcd(n, n + 1) = 1 for two consecutive integers n and n + 1?

TextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbookTextbook

Answer

The greatest common divisor (gcd) of two integers is the largest positive integer that divides both of them without leaving any remainder. Let's consider two consecutive integers, n and n + 1, where n is any integer.

 

Now, let's find the gcd of n and n + 1:

Step 1: Assume d is the gcd of n and n + 1.

Step 2: Since d divides n, there exists an integer k such that n = d * k.

Step 3: Now, let's examine n + 1: n + 1 = d * k + 1

Step 4: Since d divides both n and n + 1, it must also divide their difference: (n + 1) - n = (d * k + 1) - (d * k) = 1

Step 5: Since d divides 1 without leaving any remainder (d * 1 = 1), the gcd of n and n + 1 (d) must be 1.

 

Hence, gcd(n, n + 1) = 1 for any consecutive integers n and n + 1. This property holds true for all integer values of n, whether positive, negative, or zero.

0 0

Discussions

Post the discussion to improve the above solution.