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 - Supplementary Exercises - Page 113: 44

Answer

For Integer 22 the given statement is not true.

Work Step by Step

At most 2 squares means no squares, 1 square or 2 squares or you can say 0 squares, 1 squares or 2 squares. Let us choose the integer 22, the squares that the numbers can obtain are $1, 4, 9, 16$ (Since the terms in the non-negative terms in a sum cannot exceed the sum). First case No squares 22 is not the cube of the integer. Second case 1 square 16+6=22 ⇒ 6 is not the cube of an integer 9+13=22 ⇒ 13 is not the cube of an integer 4+18=22 ⇒ 18 is not the cube of an integer 1+21=22 ⇒ 21 is not the cube of an integer Third case 2 square 16+9=25 >22 Not possible $16+4+2=22 \Rightarrow 2$ is not the cube of an integer $16+1+5=22 \Rightarrow 5$ is not the cube of an integer $9+4+9=22 \Rightarrow 9$ is not the cube of an integer $9+1+12=22 \Rightarrow 12$ is not the cube of an integer $4+1+17=22 \Rightarrow 17$ is not the cube of an integer Conclusion: the statement is not true for 22 and thus we have disproved the statement.
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