Calculus, 10th Edition (Anton)

Published by Wiley
ISBN 10: 0-47064-772-8
ISBN 13: 978-0-47064-772-1

Chapter 13 - Partial Derivatives - 13.8 Maxima And Minima Of Functions Of Two Variables - Exercises Set 13.8 - Page 986: 19

Answer

Relative maximum at (-1,0)

Work Step by Step

$-2(1+1 x) \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=f_{x}(x, y)$ $-2 y e^{-\left(x^{2}+y^{2}+2 x\right)}=f_{y}(x, y)$ At the critical point. $-2(1+1 x) \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=0$ $-2 y \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=0$ so, $x=-1, y=0$ So, it follows: $-2 e^{-\left(x^{2}+y^{2}+2 x\right)}+4(1+x)^{2} \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=f_{x x}(x, y)$ $-2 e^{-\left(x^{2}+y^{2}+2 x\right)}+4 y^{2} \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=f_{y z}(x, y)$ $4(1+x) \cdot y \cdot e^{-\left(x^{2}+y^{2}+2 x\right)}=f_{x x}(x, y)$ $-2 e=f_{x x}(-1,0)$ $-2 e=f_{y y}(-1,0)$ $0=f_{x x}(-1,0)$ \[ D(-1,0)=4 \mathrm{e}^{2}>0, \text { and } f_{x x}(-1,0)<0 \] Relative maximum at (-1,0)
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.