Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 12 - Vectors and the Geometry of Space - 12.6 Cylinders and Quadric Surfaces - 12.6 Exercises - Page 880: 15

Answer

Hyperboloid of one sheet directed along \(x\)-axis.

Work Step by Step

We can rearrange the terms for it to be in standard form: \[ 9y^2 + 4z^2 = x^2 + 36 \\ -x^2 + 9y^2 + 4z^2 = 36 \\ \frac{-x^2}{36} + \frac{9y^2}{36} + \frac{4z^2}{36} = 1 \] Evaluated at \(x = 0\): \[ -\frac{(0)^2}{36} + \frac{9y^2}{36} + \frac{4z^2}{36} = 1 \\ \frac{y^2}{4} + \frac{z^2}{9} = 1 \\ \frac{y^2}{(2)^2} + \frac{z^2}{(3)^2} = 1 \] Ellipse of radius 2 along the \(y\)-axis and 3 along the \(z\)-axis. Evaluated at \(x = \pm 6\): \[ -\frac{(\pm 6)^2}{36} + \frac{9y^2}{36} + \frac{4z^2}{36} = 1 \\ -1 + \frac{y^2}{4} + \frac{z^2}{9} = 1 \\ \frac{y^2}{8} + \frac{z^2}{18} = 1 \\ \frac{y^2}{(2\sqrt{2})^2} + \frac{z^2}{(3\sqrt{2})^2} = 1 \] Ellipse of radius \(2\sqrt{2}\) along the \(y\)-axis and \(3\sqrt{2}\) along the \(z\)-axis.
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