Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 11: Parametric Equations and Polar Coordinates - Section 11.6 - Conic Sections - Exercises 11.6 - Page 679: 64

Answer

This is an ellipse, with the major axis on the line $x=-1$: the center is $(-1,1)$ the foci are $(-1,1\pm\sqrt{3})$ the vertices are $(-1,3)$ and $(-1, -1)$.

Work Step by Step

We group like terms $(4x^{2}+8x)+(y^{2}-2y)=-1 $ $4(x^{2}+2x)+(y^{2}-2y)=-1 \quad $ We complete the squares $4(x^{2}+2x+1)+(y^{2}-2y+1)=-1+4(1)+1 $ $4(x+1)^{2}+(y-1)^{2}=4 \quad $ We divide with $(x+1)^{2}+\displaystyle \frac{(y-1)^{2}}{4}=1$ This has the form $\quad \displaystyle \frac{x^{2}}{b^{2}}+\frac{y^{2}}{a^{2}}=1 \quad (a\gt b)$ Foci on the y-axis: $\quad a=2,\quad b=1$ Center-to-focus distance: $c=\sqrt{a^{2}-b^{2}}=\sqrt{2-1}=1$ Foci: $(0, \pm 1)$ Vertices: $(0, \pm 2)$ When $x$ is replaced with $(x+1)$, a shift to the left is made. When $y$ is replaced with $(y-1)$, a shift upward is made. $(x,y)\rightarrow(x-1,y+1)$ (A horizontal shift $\Rightarrow$ the major axis moves left to the line $x=-1$.) The center shifts to $(0-1,0+1)=(-1,1)$ The foci shift to $(-1,1\pm\sqrt{3})$ The vertices shift to $(0-1, 1\pm 2)\Rightarrow(-1,3)$ and $(-1, -1)$
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.