Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 3 - Polynomial and Rational Functions - Chapter 3 Test Prep - Review Exercises - Page 399: 40

Answer

(a) $f(2) =44\gt0$ and $f(3) =-15\lt0$. (b) $f(7) =-31\lt0$ and $f(8) =140\gt0$. (c) $x=7.236$

Work Step by Step

(a) Given $f(x)=4x^3-37x^2+50x+60$, we have $f(2)=4(2)^3-37(2)^2+50(2)+60=44\gt0$ and $f(3)=4(3)^3-37(3)^2+50(3)+60=-15\lt0$. Based on the intermediate theorem, there is a zero between 2 and 3. (b) Similarly, we have $f(7)=4(7)^3-37(7)^2+50(7)+60=-31\lt0$ and $f(8)=4(8)^3-37(8)^2+50(8)+60=140\gt0$. Based on the intermediate theorem, there is a zero between 7 and 8. (c) Graph the function as shown in the figure, we can identify the zero between 7 and 8 as $x=7.236$
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