Discrete Mathematics with Applications 4th Edition

Published by Cengage Learning
ISBN 10: 0-49539-132-8
ISBN 13: 978-0-49539-132-6

Chapter 2 - The Logic of Compound Statements - Exercise Set 2.3 - Page 61: 5

Answer

They did not telephone

Work Step by Step

If they were unsure of the address, then they would have telephoned ...(If p then q) They did not telephone ...(not q) ∴ They were sure* of the address. (not p) *read it as "not unsure" Modus Tollens: If p then q. Therefore not q implies not p
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