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 7.2 - Page 687: 71

Answer

Same center, different vertices, different foci

Work Step by Step

We are given the hyperbolas: $\dfrac{x^2}{9}-\dfrac{y^2}{1}=1$ $\dfrac{y^2}{9}-\dfrac{x^2}{1}=1$ We notice that both hyperbolas have the same $h,k,a,b,c$: $h=0$ $k=0$ $a^2=9\Rightarrow a=\sqrt 9=3$ $b^2=1\Rightarrow b=\sqrt 1=1$ $c^2=a^2+b^2$ $c^2=9+1$ $c^2=10$ $c=\sqrt{10}$ Therefore the hyperbolas have the same center $(0,0)$. Even if $a, c$ is the same, the hyperbolas have different vertices and different foci: Vertices for the first hyperbola: $(h-a,k)=(0-3,0)=(-3,0)$ $(h+a,k)=(0+3,0)=(3,0)$ Vertices for the second hyperbola: $(h,k-a)=(0,0-3)=(0,-3)$ $(h,k+a)=(0,0+3)=(0,3)$ Foci for the first hyperbola: $(h-c,k)=(0-\sqrt{10},0)=(-\sqrt{10},0)$ $(h+c,k)=(0+\sqrt{10},0)=(\sqrt{10},0)$ Foci for the second hyperbola: $(h,k-c)=(0,0-\sqrt{10})=(0,-\sqrt{10})$ $(h,k+c)=(0,0+\sqrt{10})=(0,\sqrt{10})$
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.