College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 7 - Section 7.2 - The Parabola - 7.2 Assess Your Understanding - Page 515: 24

Answer

$y^{2}=-16x$ The latus rectum has endpoints $(-4,-8)$ and $(-4,8)$

Work Step by Step

1. The focus and the vertex lie on the horizontal line $\quad y=0.\quad a=4.$ 2. The focus $(-4,0)$ is left of the vertex $(0,0)\Rightarrow$the parabola opens left. 3. By table 2, the equation is$\quad (y-k)^{2}=-4a(x-h)$ that is, $\quad y^{2}=-16x$ 4. For $x=-4, \quad y^{2}=64\quad \Rightarrow\quad y=\pm 8$ The latus rectum (line segment parallel to the directrix, containing the focus) has endpoints $(-4,-8)$ and $(-4,8)$ 5. Directrix: $\quad \quad x=h+a\quad \quad \Rightarrow\quad x=4$ We have enough details for the graph.
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