College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 7 - Conic Sections - Exercise Set 7.1 - Page 671: 44

Answer

Foci: $(4, \sqrt{21})$ and $(4, -\sqrt{21})$.

Work Step by Step

$\displaystyle \frac{(x-4)^{2}}{4}+\frac{(y-0)^{2}}{25}=1$ (major axis vertical), $a^{2}=25,$ $a=5$ $b^{2}=4$, $b=2$ Center: $(4, 0)$ $c^{2}=a^{2}-b^{2}=25-4=21,$ $c=\sqrt{21}\approx 4.583$ Foci are $c$ units above and $c$ units below the center. Foci: $(4, \sqrt{21})$ and $(4, -\sqrt{21})$.
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.