Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 3: Derivatives - Practice Exercises - Page 179: 71

Answer

$(-1,27)$ and $(2,0)$

Work Step by Step

Step 1. Find the derivative of the function $y=2x^3-3x^2-12x+20$ as $y'=6x^2-6x-12$ Step 2. For the tangent to be parallel to the x-axis, let $y'=0$; we have $6x^2-6x-12=0$ which gives $x^2-x-2=0$ or $(x+1)(x-2)=0$. Thus, we get $x_1=-1, x_2=2$ Step 3. We see that $y_1=2(-1)^3-3(-1)^2-12(-1)+20=27$ and $y_2=2(2)^3-3(2)^2-12(2)+20=0$ Step 4. Thus the answer is yes and the points are $(-1,27)$ and $(2,0)$
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.