Question: Vertex Form
y = -0.2(x - 2.47)^2 + 3.042
Factored Form
y = -0.2(x + 1.43)(x - 6.37)
Standard Form
y = -0.2x^2 + 0.988x + 1.82
Here are three equivalent equations. Use the equivalent equations to identify the key features.
The x-intercepts:
The vertex:
The y-intercept:
1. **State the problem:** We are given three equivalent forms of a quadratic function:
- Vertex form: $$y = -0.2(x - 2.47)^2 + 3.042$$
- Factored form: $$y = -0.2(x + 1.43)(x - 6.37)$$
- Standard form: $$y = -0.2x^2 + 0.988x + 1.82$$
We need to identify the key features: the x-intercepts, the vertex, and the y-intercept.
2. **Find the x-intercepts:**
The x-intercepts occur where $$y=0$$.
Using the factored form:
$$0 = -0.2(x + 1.43)(x - 6.37)$$
Since $$-0.2 \neq 0$$, the solutions come from:
$$x + 1.43 = 0 \implies x = -1.43$$
$$x - 6.37 = 0 \implies x = 6.37$$
So, the x-intercepts are $$x = -1.43$$ and $$x = 6.37$$.
3. **Find the vertex:**
The vertex form is:
$$y = a(x - h)^2 + k$$
where $$(h,k)$$ is the vertex.
From the vertex form given:
$$y = -0.2(x - 2.47)^2 + 3.042$$
So, the vertex is at:
$$(2.47, 3.042)$$
4. **Find the y-intercept:**
The y-intercept occurs when $$x=0$$.
Using the standard form:
$$y = -0.2(0)^2 + 0.988(0) + 1.82 = 1.82$$
So, the y-intercept is:
$$(0, 1.82)$$
5. **Summary of key features:**
- **x-intercepts:** $$-1.43$$ and $$6.37$$
- **Vertex:** $$(2.47, 3.042)$$
- **y-intercept:** $$(0, 1.82)$$
6. **Graph/table shapes:**
- Since $$a = -0.2 < 0$$, the parabola opens downward.
- The vertex is a maximum point.
This completes the identification of the key features.