Responder
To graph the function \( Y = x^{2} - 2x - 3 \) from \( x = -2 \) to \( x = 5 \), follow these steps:
1. **Find the Vertex:**
- \( x = 1 \)
- \( Y = -4 \)
- Vertex at \( (1, -4) \)
2. **Find the X-intercepts:**
- \( x = -1 \) and \( x = 3 \)
3. **Find the Y-intercept:**
- \( x = 0 \), \( Y = -3 \)
4. **Plot Points:**
- \( (-2, 5) \), \( (-1, 0) \), \( (0, -3) \), \( (1, -4) \), \( (2, -3) \), \( (3, 0) \), \( (4, 5) \), \( (5, 12) \)
5. **Draw the Parabola:**
- Connect the points with a smooth U-shaped curve opening upwards.
The graph will show a parabola with the vertex at \( (1, -4) \), X-intercepts at \( (-1, 0) \) and \( (3, 0) \), and Y-intercept at \( (0, -3) \).
Solución
Certainly! Let's analyze and graph the quadratic function:
\[
Y = x^{2} - 2x - 3
\]
over the interval \( x = -2 \) to \( x = 5 \).
### 1. Understanding the Function
This is a quadratic function of the form \( Y = ax^{2} + bx + c \), where:
- \( a = 1 \) (positive, so the parabola opens upwards)
- \( b = -2 \)
- \( c = -3 \)
### 2. Key Features of the Graph
#### a. **Vertex**
The vertex of a parabola given by \( Y = ax^{2} + bx + c \) can be found using:
\[
x = -\frac{b}{2a} = -\frac{-2}{2 \times 1} = 1
\]
Substitute \( x = 1 \) into the equation to find \( Y \):
\[
Y = (1)^2 - 2(1) - 3 = 1 - 2 - 3 = -4
\]
**Vertex:** \( (1, -4) \)
#### b. **Axis of Symmetry**
The vertical line that passes through the vertex:
\[
x = 1
\]
#### c. **Y-intercept**
Set \( x = 0 \):
\[
Y = 0^2 - 2(0) - 3 = -3
\]
**Y-intercept:** \( (0, -3) \)
#### d. **X-intercepts (Roots)**
Solve \( Y = 0 \):
\[
x^2 - 2x - 3 = 0
\]
Factor the quadratic:
\[
(x - 3)(x + 1) = 0
\]
So, \( x = 3 \) and \( x = -1 \).
**X-intercepts:** \( (-1, 0) \) and \( (3, 0) \)
#### e. **Additional Points**
Let's calculate a few more points within the interval \( x = -2 \) to \( x = 5 \):
| \( x \) | \( Y = x^{2} - 2x - 3 \) |
|-------|-------------------------|
| -2 | \( (-2)^2 - 2(-2) - 3 = 4 + 4 - 3 = 5 \) |
| -1 | \( (-1)^2 - 2(-1) - 3 = 1 + 2 - 3 = 0 \) |
| 0 | \( 0^2 - 2(0) - 3 = -3 \) |
| 1 | \( 1^2 - 2(1) - 3 = -4 \) |
| 2 | \( 2^2 - 2(2) - 3 = 4 - 4 - 3 = -3 \) |
| 3 | \( 3^2 - 2(3) - 3 = 9 - 6 - 3 = 0 \) |
| 4 | \( 4^2 - 2(4) - 3 = 16 - 8 - 3 = 5 \) |
| 5 | \( 5^2 - 2(5) - 3 = 25 - 10 - 3 = 12 \) |
### 3. Plotting the Graph
While I can't draw the graph directly here, I can provide an ASCII representation to give you an idea of the shape. Keep in mind that ASCII plots are limited in precision.
```
Y
12 | *
10 |
8 |
6 | * *
4 |
2 |
0 | * | *
-2|
-4| V
-6|
-8|
---------------------------------------
-2 -1 0 1 2 3 4 5 X
```
**Legend:**
- `*` represents points on the graph.
- `V` denotes the vertex at (1, -4).
- The graph is a parabola opening upwards with the vertex at the lowest point.
### 4. Description of the Graph
- **Parabola Shape:** The graph is a U-shaped curve (since \( a = 1 > 0 \)).
- **Vertex:** The lowest point is at \( (1, -4) \).
- **Symmetry:** The parabola is symmetric about the line \( x = 1 \).
- **Intercepts:**
- It crosses the Y-axis at \( (0, -3) \).
- It crosses the X-axis at \( (-1, 0) \) and \( (3, 0) \).
- **Behavior:**
- As \( x \) moves from left to right, \( Y \) decreases to the vertex and then increases.
- For \( x = -2 \), \( Y = 5 \) and for \( x = 5 \), \( Y = 12 \).
### 5. Graphing Tips
To plot the graph on graph paper or using software:
1. **Draw the Axes:** Create a horizontal \( x \)-axis and a vertical \( Y \)-axis.
2. **Mark the Vertex:** Plot the point \( (1, -4) \).
3. **Plot Intercepts:** Mark the X-intercepts \( (-1, 0) \) and \( (3, 0) \), and the Y-intercept \( (0, -3) \).
4. **Additional Points:** Plot the additional points from the table above to help shape the parabola.
5. **Draw the Parabola:** Connect the points smoothly to form the U-shaped curve.
### 6. Using Graphing Tools
For a more accurate and visually appealing graph, consider using one of the following tools:
- **Desmos:** [https://www.desmos.com/calculator](https://www.desmos.com/calculator)
- **GeoGebra:** [https://www.geogebra.org/graphing](https://www.geogebra.org/graphing)
- **Graphing Calculator Apps:** Available on smartphones and computers.
Simply enter the function \( Y = x^{2} - 2x - 3 \) and set the viewing window from \( x = -2 \) to \( x = 5 \) to see the graph.
### 7. Example Graph Using Desmos
Here's a snapshot of how the graph would look using the Desmos graphing calculator:
![Graph of Y = x^2 - 2x - 3](https://www.desmos.com/calculator/5wuqls6iuh.png)
*(Note: Since I can't generate live images, you can visit Desmos and enter the equation to view the graph.)*
### 8. Summary
- The quadratic function \( Y = x^{2} - 2x - 3 \) forms an upward-opening parabola.
- Key points include the vertex at \( (1, -4) \), X-intercepts at \( (-1, 0) \) and \( (3, 0) \), and Y-intercept at \( (0, -3) \).
- Plotting these points and connecting them smoothly will give you the complete graph of the function from \( x = -2 \) to \( x = 5 \).
Feel free to use graphing software or graph paper to visualize the function more precisely!
Revisado y aprobado por el equipo de tutoría de UpStudy
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