Calculus: Early Transcendentals (2nd Edition)

Published by Pearson
ISBN 10: 0321947347
ISBN 13: 978-0-32194-734-5

Chapter 1 - Functions - 1.3 Inverse, Exponential, and Logarithmic Functions - 1.3 Exercises - Page 38: 85

Answer

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Work Step by Step

We have to prove the statement: $\log_b \dfrac{x}{y}=\log_b x-\log_b y$ a) Let $x=b^p$ $y=b^q$ Solve these two equations for $p$ and $q$: $\log_b x=\log_b b^p$ $\log_b x=p\log_b b$ $\log_b x=p$ $\log_b y=\log_b b^q$ $\log_b y=q\log_b b$ $\log_b y=q$ b) Use the property E2 for exponents to express $\dfrac{x}{y}$ in terms of $b,p,q$: $\dfrac{x}{y}=\dfrac{b^p}{b^q}$ $\dfrac{x}{y}=b^{p-q}$ c) Compute $\log_b \dfrac{x}{y}$ and simplify: $\log_b \dfrac{x}{y}=\log_b b^{p-q}$ $\log_b \dfrac{x}{y}=(p-q)\log_b b$ $\log_b \dfrac{x}{y}=p-q$ $\log_b \dfrac{x}{y}=\log_b x-\log_b y$
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