## Precalculus (6th Edition) Blitzer

Step 1. Graph the equation as shown in the figure. Step 2. We can identify from the given equation that $a=3, b=1$; thus $c=\sqrt {3^2+1^2}=\sqrt {10}$ Step 3. As the center of the ellipse is at $(0,0)$ and the major axis is horizontal, the foci are $(\pm\sqrt {10},0)$ and the asymptotes are $y=\pm \frac{1}{3}x$ as shown in the figure.