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: 63

Answer

This is an ellipse, with the main axis on the line $y=1$: the center is $(1,1)$ the foci are $(2, 1)$ and $(0,1)$ the vertices are $(1\pm\sqrt{2},1)$

Work Step by Step

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