Responder
To sketch the graph of the function:
\[
g(x) = \begin{cases}
x + 1, & \text{if } x \leq -4 \\
\frac{1}{2}x - 5, & \text{if } x > -4
\end{cases}
\]
1. **For \( x \leq -4 \)**:
- Plot the line \( y = x + 1 \).
- At \( x = -4 \), \( g(-4) = -3 \).
2. **For \( x > -4 \)**:
- Plot the line \( y = \frac{1}{2}x - 5 \).
- As \( x \) approaches \(-4\) from the right, \( g(x) \) approaches \(-7\).
3. **Discontinuity at \( x = -4 \)**:
- At \( x = -4 \), there's a jump from \( y = -3 \) to \( y \) approaching \(-7\).
4. **Key Points**:
- \( (-4, -3) \) (closed circle)
- \( (-5, -4) \) (another point on the first line)
- \( (0, -5) \) (y-intercept of the second line)
- \( (2, -4) \) (another point on the second line)
5. **Graph Description**:
- Two separate lines connected by a jump at \( x = -4 \).
- The first line is steeper for \( x \leq -4 \).
- The second line is less steep for \( x > -4 \).
This graph shows a piecewise function with a jump discontinuity at \( x = -4 \).
Solución
To sketch the graph of the piecewise function:
\[
g(x) = \begin{cases}
x + 1, & \text{if } x \leq -4 \\
\frac{1}{2}x - 5, & \text{if } x > -4
\end{cases}
\]
let's analyze each part of the function and understand how they connect.
### 1. Analyzing Each Piece
#### a. For \( x \leq -4 \): \( g(x) = x + 1 \)
- **Type of Function**: This is a linear function with a slope of 1 and a y-intercept at (0, 1).
- **Key Point at \( x = -4 \)**:
\[
g(-4) = (-4) + 1 = -3
\]
- **End Behavior**: As \( x \) decreases (goes to the left), \( g(x) \) decreases linearly.
#### b. For \( x > -4 \): \( g(x) = \frac{1}{2}x - 5 \)
- **Type of Function**: This is also a linear function but with a slope of \( \frac{1}{2} \) and a y-intercept at (0, -5).
- **Limit as \( x \) Approaches -4 from the Right**:
\[
\lim_{x \to -4^+} g(x) = \frac{1}{2}(-4) - 5 = -2 - 5 = -7
\]
- **End Behavior**: As \( x \) increases (goes to the right), \( g(x) \) increases gradually.
### 2. Continuity at \( x = -4 \)
At \( x = -4 \), we need to check if the function is continuous.
- **Left-hand Limit** (\( x \to -4^- \)):
\[
\lim_{x \to -4^-} g(x) = (-4) + 1 = -3
\]
- **Right-hand Limit** (\( x \to -4^+ \)):
\[
\lim_{x \to -4^+} g(x) = -7
\]
- **Function Value**:
\[
g(-4) = -3
\]
Since the left-hand limit (\(-3\)) does not equal the right-hand limit (\(-7\)), there is a **jump discontinuity** at \( x = -4 \).
### 3. Sketching the Graph
Below is a descriptive sketch of the graph:
```
y
|
| *
| /
| /
| /
| /
| /
| /
| /
| /
| /
| /
| /
| /
| /
|-----------*-------------- x
| (-4, -3) (Jump to (-4, -7))
|
```
**Explanation**:
- **For \( x \leq -4 \)**: Plot the line \( y = x + 1 \). It passes through the point \((-4, -3)\). This line extends to the left.
- **For \( x > -4 \)**: Plot the line \( y = \frac{1}{2}x - 5 \). The value approaches \(-7\) as \( x \) approaches \(-4 \) from the right, but at \( x = -4 \), the function value is \(-3\). This creates a jump from \(-3\) to values approaching \(-7\).
- **Discontinuity**: At \( x = -4 \), there's an open circle at \((-4, -7)\) and a closed circle at \((-4, -3)\) to indicate the jump.
### 4. Key Points to Plot
- **For \( x \leq -4 \)**:
- Point at \( (-4, -3) \)
- Another point at \( (-5, -4) \) (since \( g(-5) = -5 + 1 = -4 \))
- **For \( x > -4 \)**:
- Point approaching \( (-4, -7) \) as \( x \) approaches \(-4\) from the right
- Point at \( (0, -5) \) (y-intercept)
- Point at \( (2, -4) \) (since \( g(2) = \frac{1}{2}(2) - 5 = -4 \))
### 5. Summary
- **Two distinct linear segments**:
- A steeper line for \( x \leq -4 \)
- A less steep line for \( x > -4 \)
- **Jump Discontinuity at \( x = -4 \)**
- **No overlapping points**; the function switches from one line to the other abruptly.
This piecewise function models a situation where the behavior changes at \( x = -4 \), resulting in two separate linear trends connected by a jump.
Revisado y aprobado por el equipo de tutoría de UpStudy
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