Quadratic Functions
1. Problem 1: For the function $f(x) = -x^2 - 2x - 3$
- **Vertex**: Use vertex formula $x = -\frac{b}{2a} = -\frac{-2}{2(-1)} = 1$
- Substitute $x=1$ to find $y$: $f(1) = -(1)^2 - 2(1) - 3 = -1 - 2 - 3 = -6$
- Vertex is $(1, -6)$
- **Opening**: Since $a = -1 < 0$, the parabola opens downward.
- **Vertex point type**: It's a maximum point as parabola opens downward.
- **Axis of symmetry** equation: $x=1$
- **Domain**: All real numbers, written $(-\infty, \infty)$.
- **Range**: Since vertex is max $y=-6$, range is $(-\infty, -6]$.
2. Problem 2: For $f(x) = 2x^2 + 4x - 3$
- Vertex formula: $x = -\frac{4}{2(2)} = -1$
- $f(-1) = 2(-1)^2 + 4(-1) - 3 = 2 - 4 - 3 = -5$
- Vertex: $(-1, -5)$
- Opening: $a = 2 > 0$ so opens upward
- Vertex point type: minimum
- Axis of symmetry: $x = -1$
- Domain: $(-\infty, \infty)$
- Range: $[-5, \infty)$
3. Problem 3: $f(x) = (x+2)^2 + 3$
- Vertex form shows vertex directly: $(-2, 3)$
- Opening: $a=1 > 0$ opens upward
- Vertex type: minimum
- Domain: $(-\infty, \infty)$
- Range: $[3, \infty)$
4. Convert $f(x) = x^2 + 2x - 1$ to vertex form
- Complete the square:
$$x^2 + 2x = (x+1)^2 - 1$$
- So,
$$f(x) = (x+1)^2 - 1 - 1 = (x+1)^2 - 2$$
5. Convert $f(x) = (x+2)^2 - 4$ to standard form
- Expand:
$$(x+2)^2 - 4 = x^2 + 4x + 4 - 4 = x^2 + 4x$$
6. Convert $f(x) = 2(x-10)^2 + 14$ to standard form
- Expand:
$$2(x-10)^2 + 14 = 2(x^2 - 20x + 100) + 14 = 2x^2 - 40x + 200 + 14 = 2x^2 - 40x + 214$$
Summary:
- Vertex points and graph shapes explained.
- Axis of symmetry and range/domain detailed.
- Conversion between standard and vertex forms demonstrated with full steps.