Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 10 - Analytic Geometry - Chapter 10 Test Prep - Review Exercises - Page 1002: 54

Answer

$$\frac{{{x^2}}}{{40}} + \frac{{{y^2}}}{{49}} = 1$$

Work Step by Step

$$\eqalign{ & {\text{ellipse with foci at }}\left( {0, \pm 3} \right){\text{and vertex }}\left( {0, - 7} \right) \cr & {\text{The coordinates of the foci are }}\left( {0, \pm c} \right),{\text{ then}} \cr & {\text{The equation of the ellipse is of the form }}\frac{{{x^2}}}{{{b^2}}} + \frac{{{y^2}}}{{{a^2}}} = 1 \cr & {\text{Foci at }}\left( {0, \pm 3} \right),\,\,\left( {0, \pm c} \right) \to c = 3 \cr & {\text{Vertices }}\left( {0, \pm a} \right),\,\left( {0, - 7} \right) \to a = 7 \cr & {b^2} = {a^2} - {c^2} \cr & {b^2} = {7^2} - {3^2} = 40 \cr & \cr & {\text{The equation of the ellipse is}} \cr & \frac{{{x^2}}}{{40}} + \frac{{{y^2}}}{{49}} = 1 \cr} $$
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