1. The problem asks for the domain of the difference function $f - g$. 2. The domain of $f - g$ is the intersection of the domains of $f$ and $g$. 3. Given the choices, the domain that fits the difference function is $(-\infty, 7]$. 4. Therefore, the answer is Choice C: $(-\infty, 7]$. --- 11. Given the graph of a downward-opening parabola with vertex at $(-2, 9)$: (a) The vertex is $(-2, 9)$. (b) Since the parabola opens downward, the range is $(-\infty, 9]$. (c) The function is decreasing on the interval $(-\infty, -2)$. (d) The equation of the parabola is $y = -x^2 - 4x + 5$ (Choice A). Final answers: - Domain of $f - g$: $(-\infty, 7]$ - Vertex: $(-2, 9)$ - Range: $(-\infty, 9]$ - Decreasing interval: $(-\infty, -2)$ - Equation: $y = -x^2 - 4x + 5$