![y = - {x}^(2) - 8x - 16](https://img.qammunity.org/2021/formulas/mathematics/high-school/abhaaccl6smvhf7w1f3t9aeagntn63jt5u.png)
![(d)/(dx) ( - {x}^(2) - 8x - 16) \\ - 2x - 8 = 0 \\ - 2x = 8 \\ x = - 4](https://img.qammunity.org/2021/formulas/mathematics/high-school/awd942idyizaqpil38tb1s5pel2jmo7450.png)
Axis of Symmetry is x = h. Therefore the axis of symmetry is x = -4
![y = - ( - {4})^(2) - 8( - 4) - 16 \\ y = - 16 + 32 - 16 \\ y = 0](https://img.qammunity.org/2021/formulas/mathematics/high-school/6eixbxpbooy3n9v86cwyxymyz599epehs4.png)
The vertex is at (h, k). Therefore the vertex is at (-4,0)
Domain for Quadratic Function is all set of real number.
Range is from minimun value to maximum value. However, downward parabola doesn't have minimum value. Therefore the range is less or equal than the vertex for k value.
The range is y<= 0