Calculus, 10th Edition (Anton)

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

Chapter 13 - Partial Derivatives - 13.6 Directional Derivatives And Gradients - Exercises Set 13.6 - Page 969: 62

Answer

Vector opposite the gradient: $-(3 \mathbf{i}+2 \mathbf{j})=\mathbf{V}$ Unit vector: $-\frac{1}{\sqrt{13}}(\mathbf{i}+3 \mathbf{j})=\mathbf{v}$ Rate of change: $-\sqrt{13} . e^{6}=-\|\nabla f(2,3)\|$

Work Step by Step

$f$ increases more quickly in the positive direction of $\nabla f(x, y)$ \[ \begin{array}{l} f_{x}(x, y)=y e^{x y} \\ f_{x}(2,3)=3 e^{6} \\ x e^{x y}=f_{y}(x, y) \\ 2 e^{6}=f_{y}(2,3) \end{array} \] \[ (3 \mathbf{i}+2 \mathbf{j})e^{6}=\nabla f(2,3) \] Vector opposite the gradient: $-(3 \mathbf{i}+2 \mathbf{j})=\mathbf{V}$ Unit vector: $-\frac{1}{\sqrt{13}}(\mathbf{i}+3 \mathbf{j})=\mathbf{v}$ Rate of change: $-\sqrt{13} . e^{6}=-\|\nabla f(2,3)\|$
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.