1. **State the problem:** We are given two quadratic functions:
- $f(x) = (x - 2)^2 + 5$
- $g(x) = -2(x + 3)^2 + 8$
We need to analyze each parabola by answering questions about their properties.
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### For $f(x) = (x - 2)^2 + 5$:
1. **Opens up or down?**
Since the coefficient of the squared term is positive (1), the parabola opens **upwards**.
2. **Axis of symmetry:**
The axis of symmetry is the vertical line through the vertex. For $f(x) = (x - h)^2 + k$, axis is $x = h$.
Here, $h = 2$, so axis of symmetry is:
$$x = 2$$
3. **Vertex:**
The vertex is at $(h, k)$, so:
$$(2, 5)$$
4. **y-intercept:**
Set $x=0$:
$$f(0) = (0 - 2)^2 + 5 = 4 + 5 = 9$$
So y-intercept is:
$$(0, 9)$$
5. **Zeros:**
Set $f(x) = 0$:
$$(x - 2)^2 + 5 = 0 \\ (x - 2)^2 = -5$$
Since square of a real number cannot be negative, there are **no real zeros**.
6. **Max or min?**
Since it opens upwards, vertex is a **minimum** point.
Minimum value is $5$ at $x=2$.
7. **Domain $D$:**
All real numbers:
$$(-\infty, +\infty)$$
8. **Range $R$:**
Since minimum is 5 and parabola opens up:
$$[5, +\infty)$$
9. **Standard form:**
Expand:
$$f(x) = (x - 2)^2 + 5 = (x^2 - 4x + 4) + 5 = x^2 - 4x + 9$$
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### For $g(x) = -2(x + 3)^2 + 8$:
1. **Opens up or down?**
Coefficient of squared term is $-2$ (negative), so it opens **downwards**.
2. **Axis of symmetry:**
For $g(x) = a(x - h)^2 + k$, axis is $x = h$.
Here, $h = -3$, so:
$$x = -3$$
3. **Vertex:**
At $(h, k) = (-3, 8)$
4. **y-intercept:**
Set $x=0$:
$$g(0) = -2(0 + 3)^2 + 8 = -2(9) + 8 = -18 + 8 = -10$$
So y-intercept is:
$$(0, -10)$$
5. **Zeros:**
Set $g(x) = 0$:
$$-2(x + 3)^2 + 8 = 0 \\ -2(x + 3)^2 = -8 \\ (x + 3)^2 = 4 \\ x + 3 = \pm 2$$
So zeros are:
$$x = -3 + 2 = -1$$
$$x = -3 - 2 = -5$$
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**Final answers:**
$f(x)$:
- Opens up
- Axis: $x=2$
- Vertex: $(2,5)$
- y-intercept: $(0,9)$
- Zeros: none
- Min at $y=5$
- Domain: $(-\infty,+\infty)$
- Range: $[5,+\infty)$
- Std form: $x^2 - 4x + 9$
$g(x)$:
- Opens down
- Axis: $x=-3$
- Vertex: $(-3,8)$
- y-intercept: $(0,-10)$
- Zeros: $x=-1, x=-5$
Parabola Properties 0B940A
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