## Precalculus (6th Edition) Blitzer

domain $(-\infty,3]$, range $(-\infty, \infty)$, not a function.
Step 1. Rewrite the equation as $(y-1)^2=-\frac{1}{4}(x-3)$ We see that the parabola opens to the left with a vertex at $(3,1)$. Step 2. We can find the domain as $(-\infty,3]$ and range as $(-\infty, \infty)$ Step 3. The relation is not a function as it will fail a vertical line test.