## Precalculus (6th Edition) Blitzer

Step 1. Rewrite the equation as $4(x^2+6x+9)+9(y^2-4y+4)=36+36-36$ or $\frac{(x+3)^2}{9}+\frac{(y-2)^2}{4}=1$ We can identify $a=3, b=2, c=\sqrt {9-4}=\sqrt 5$ with a center at $(-3,2)$ Step 2. See graph; we can locate the foci at $(-3\pm\sqrt 5,2)$