Finite Math and Applied Calculus (6th Edition)

Published by Brooks Cole
ISBN 10: 1133607705
ISBN 13: 978-1-13360-770-0

Chapter 9 - Section 9.3 - Logarithmic Functions and Models - Exercises - Page 660: 72

Answer

Sample answer: We need logarithms to solve some exponential equations (equations where the variable is in the exponent).

Work Step by Step

We need logarithms to solve exponential equations (equations where the variable is in the exponent). For example, to find $t$ in $200=112(0.025)^{4t}$, we divide with $112$: $200/112=(0.025)^{4t}$ We need to take the logarithm of both sides, using the rule $\log_{b}\left(x^{r}\right)=r\log_{b}x$ This allows for $t$ to exit the exponent and the equation becomes: $\log(200/112)=4t\cdot\log(0.025)$ We finish by dividing both sides with $4\log(0.025)$, which will allow us to solve for $t$.
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