Quadratic Properties 4Bf80A
1. Problem: Find the zeroes, domain, range, axis of symmetry, and vertex for the quadratic function $y = x^2 - 9$.
2. Formula and rules:
- Zeroes are found by solving $y=0$.
- Domain of any quadratic function is all real numbers: $(-\infty, \infty)$.
- Range depends on the vertex and whether parabola opens up or down.
- Axis of symmetry formula: $x = -\frac{b}{2a}$ for $ax^2 + bx + c$.
- Vertex coordinates: $(h, k)$ where $h$ is axis of symmetry and $k = f(h)$.
3. Find zeroes:
Set $y=0$:
$$x^2 - 9 = 0$$
$$x^2 = 9$$
$$x = \pm 3$$
Zeroes are $x=3$ and $x=-3$.
4. Domain:
All real numbers: $(-\infty, \infty)$.
5. Axis of symmetry:
Here $a=1$, $b=0$, so
$$x = -\frac{0}{2 \times 1} = 0$$
6. Vertex:
Calculate $y$ at $x=0$:
$$y = 0^2 - 9 = -9$$
Vertex is at $(0, -9)$.
7. Range:
Since $a=1 > 0$, parabola opens upward, so minimum value is vertex $y=-9$.
Range is $[-9, \infty)$.
Final answer:
- Zeroes: $x=3, -3$
- Domain: $(-\infty, \infty)$
- Range: $[-9, \infty)$
- Axis of symmetry: $x=0$
- Vertex: $(0, -9)$