1. **Problem 5a:** Given the function $y = x \cdot \left(x - \frac{3}{4}\right)$, find the zeros, vertex, stretch factor, general form, and y-intercept.
2. **Formula and rules:**
- To find zeros, set $y=0$ and solve for $x$.
- The vertex of a parabola in factored form $y = a(x - x_1)(x - x_2)$ is at $x = \frac{x_1 + x_2}{2}$.
- The stretch factor is the coefficient $a$.
- The general form is $y = ax^2 + bx + c$.
- The y-intercept is found by evaluating $y$ at $x=0$.
3. **Find zeros:**
$$0 = x \cdot \left(x - \frac{3}{4}\right)$$
Zeros are $x=0$ and $x=\frac{3}{4}$.
4. **Find vertex:**
$$x_{vertex} = \frac{0 + \frac{3}{4}}{2} = \frac{3}{8}$$
Evaluate $y$ at $x=\frac{3}{8}$:
$$y = \frac{3}{8} \cdot \left(\frac{3}{8} - \frac{3}{4}\right) = \frac{3}{8} \cdot \left(-\frac{3}{8}\right) = -\frac{9}{64}$$
Vertex is $\left(\frac{3}{8}, -\frac{9}{64}\right)$.
5. **Stretch factor:**
Coefficient $a=1$.
6. **General form:**
Expand:
$$y = x^2 - \frac{3}{4}x$$
7. **Y-intercept:**
At $x=0$,
$$y = 0$$
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1. **Problem 6a:** Show that the three forms represent the same function for the first example:
- Vertex form: $y = (x - 0.5)^2 - 2.25$
- General form: $y = x^2 - x - 2$
- Factored form: $y = (x - 2)(x + 1)$
2. **Expand vertex form:**
$$y = (x - 0.5)^2 - 2.25 = x^2 - 2 \cdot 0.5 x + 0.5^2 - 2.25 = x^2 - x + 0.25 - 2.25 = x^2 - x - 2$$
Matches general form.
3. **Expand factored form:**
$$y = (x - 2)(x + 1) = x^2 + x - 2x - 2 = x^2 - x - 2$$
Matches general form.
Thus, all three forms represent the same function.
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1. **Problem 7a:** Find equations of parabolas with zeros $x_1=1$ and $x_2=3$.
2. **General form from zeros:**
$$f(x) = a(x - x_1)(x - x_2) = a(x - 1)(x - 3)$$
3. **Choose $a=1$ for simplicity:**
$$f(x) = (x - 1)(x - 3) = x^2 - 4x + 3$$
4. **Alternative parabola:**
Choose $a = -1$:
$$f(x) = - (x - 1)(x - 3) = -x^2 + 4x - 3$$
These are two parabolas with the given zeros.
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**Final answers:**
**5a:** Zeros: $0$, $\frac{3}{4}$; Vertex: $\left(\frac{3}{8}, -\frac{9}{64}\right)$; Stretch factor: $1$; General form: $y = x^2 - \frac{3}{4}x$; Y-intercept: $0$.
**6a:** The three forms represent the same function $y = x^2 - x - 2$.
**7a:** Parabolas with zeros $1$ and $3$ are $f(x) = (x - 1)(x - 3)$ and $f(x) = - (x - 1)(x - 3)$.
Parabola Forms 85D471
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