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: 40


Foci: $(-1, -2)$ and $(7, -2)$.

Work Step by Step

Bring to stadard form (divide with 1$8$) $\displaystyle \frac{(x+3)^{2}}{18}+\frac{(y-2)^{2}}{2}=1$ $a^{2}=18,$ (main axis horizontal), $a=\sqrt{18}=3\sqrt{2}\approx 4.24$ $b^{2}=2$, $b=\sqrt{2}\approx 1.41$ Center: $(h,k)=(3,-2)$ $c^{2}=a^{2}-b^{2}=18-2-16,$ $c=4$ Foci are $c$ units right and $c$ units left of center. Foci: $(-1, -2)$ and $(7, -2)$.
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