## Calculus: Early Transcendentals 8th Edition

Published by Cengage Learning

# Chapter 14 - Section 14.3 - Partial Derivatives - 14.3 Exercise: 7

#### Answer

(a) Positive (b) Negative

#### Work Step by Step

(a) The second derivative shows concavity. As we move along the x-axis at the point $(-1, 2)$, the graph is shown to be concave up . This shows that $f_{xx}$ is positive. (b) The second derivative shows concavity. As we move along the y-axis at the point $(-1, 2)$, the graph is shown to be concave down. This shows that $f_{yy}$ is negative.

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