Chapter 9 - Quadratic Functions and Equations - 9-1 Quadratic Graphs and Their Properties - Practice and Problem-Solving Exercises - Page 550: 31

Domain: All Real Numbers Range: $y\leq-9$

For a parabola, the domain is almost always all real numbers. Here, the y value of the vertex is -9. Because of the -3/4 in from of the $x^2$, the vertex is the maximum value. Thus, the range includes all values less than the y value of the vertex.