[tex] {x}^{2} - 2 {x}^{2} - 4 \\ - {x}^{2} - 4[/tex]
The Quadratic Function has the domain as the set of all real numbers.
For the range, start from minimum value to maximum value.
But because the parabola is downward as a < 0. Thus, there are no minimum value but the maximum value instead.
Therefore the range is y <= -4
