Discrete Mathematics with Applications 4th Edition

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

Chapter 7 - Functions - Exercise Set 7.3 - Page 427: 12

Answer

See explanation

Work Step by Step

**Answer Explanation** Recall that by definition of the logarithm, \(\log_b(a)\) is “the exponent you put on \(b\) to get \(a\).” Formally, \(\log_b(a) = y\) means exactly that \(b^y = a\), assuming \(b>0\) and \(b \neq 1\). --- **(a) Why \(\log_b\bigl(b^x\bigr) = x\)** 1. Look at the expression \(\log_b\bigl(b^x\bigr)\). By definition, \(\log_b\bigl(b^x\bigr)\) is the exponent to which you raise \(b\) to obtain \(b^x\). 2. But we already know that raising \(b\) to the power \(x\) gives \(b^x\). 3. Therefore, the exponent in question must be \(x\). Hence \(\log_b\bigl(b^x\bigr) = x\). --- **(b) Why \(b^{\log_b(x)} = x\)** 1. By definition, \(\log_b(x)\) is the exponent that makes \(b\) become \(x\). In other words, \(\log_b(x) = y\) means \(b^y = x\). 2. If you take \(b\) raised to \(\log_b(x)\), you are literally “raising \(b\) to the exponent that gives \(x\).” 3. Hence \(b^{\log_b(x)} = x\). Both parts are simply restatements of the fact that “logarithm and exponentiation (with the same base) are inverse operations.”
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.