Answer
To sketch the given parabolas, follow these steps for each function:
1. **Identify the Vertex** \((h, k)\) from the vertex form \( y = a(x - h)^2 + k \).
2. **Determine the Direction** based on the sign of \( a \):
- If \( a > 0 \), the parabola opens upwards.
- If \( a < 0 \), it opens downwards.
3. **Draw the Axis of Symmetry** at \( x = h \).
4. **Plot Additional Points** by choosing \( x \)-values on either side of the vertex and calculating corresponding \( y \)-values.
5. **Sketch the Parabola** using the vertex, axis of symmetry, and plotted points.
Apply these steps to each of the six functions to accurately sketch their graphs.
Solution
Certainly! Let's analyze and sketch each of the given quadratic functions. Quadratic functions are typically expressed in the **vertex form**:
\[ y = a(x - h)^2 + k \]
where:
- \((h, k)\) is the **vertex** of the parabola.
- \(a\) determines the **direction** and **width** of the parabola:
- If \(a > 0\), the parabola **opens upwards**.
- If \(a < 0\), the parabola **opens downwards**.
- The larger \(|a|\) is, the **narrower** the parabola.
- The smaller \(|a|\) is (but \(a \neq 0\)), the **wider** the parabola.
Let's go through each function step-by-step:
---
### **a) \( y = 2(x - 3)^2 - 2 \)**
- **Vertex Form Analysis:**
- \( a = 2 \) (positive, so parabola opens **upwards**)
- \( h = 3 \)
- \( k = -2 \)
- **Vertex:** \( (3, -2) \)
- **Axis of Symmetry:** \( x = 3 \)
- **Width:** Since \(|a| = 2 > 1\), the parabola is **narrower** than the standard \( y = x^2 \).
- **Sketching Steps:**
1. Plot the vertex at \( (3, -2) \).
2. Draw the axis of symmetry \( x = 3 \).
3. Since \(a = 2\), choose points on either side of the vertex (e.g., \( x = 2 \) and \( x = 4 \)) to find corresponding \( y \)-values.
4. Plot these points and sketch the upward-opening parabola.
---
### **b) \( f(x) = -(x + 2)^2 + 4 \)**
- **Vertex Form Analysis:**
- \( a = -1 \) (negative, so parabola opens **downwards**)
- \( h = -2 \)
- \( k = 4 \)
- **Vertex:** \( (-2, 4) \)
- **Axis of Symmetry:** \( x = -2 \)
- **Width:** Since \(|a| = 1\), the parabola has the **standard width**.
- **Sketching Steps:**
1. Plot the vertex at \( (-2, 4) \).
2. Draw the axis of symmetry \( x = -2 \).
3. Choose points on either side of the vertex (e.g., \( x = -3 \) and \( x = -1 \)) to find corresponding \( y \)-values.
4. Plot these points and sketch the downward-opening parabola.
---
### **c) \( h(x) = -(x - 3)^2 + 5 \)**
- **Vertex Form Analysis:**
- \( a = -1 \) (negative, so parabola opens **downwards**)
- \( h = 3 \)
- \( k = 5 \)
- **Vertex:** \( (3, 5) \)
- **Axis of Symmetry:** \( x = 3 \)
- **Width:** Standard width since \(|a| = 1\).
- **Sketching Steps:**
1. Plot the vertex at \( (3, 5) \).
2. Draw the axis of symmetry \( x = 3 \).
3. Select points around the vertex (e.g., \( x = 2 \) and \( x = 4 \)) to determine \( y \)-values.
4. Plot these points and draw the downward-opening parabola.
---
### **d) \( p(x) = \frac{1}{2}(x + 2)^2 + 2 \)**
- **Vertex Form Analysis:**
- \( a = \frac{1}{2} \) (positive, so parabola opens **upwards**)
- \( h = -2 \)
- \( k = 2 \)
- **Vertex:** \( (-2, 2) \)
- **Axis of Symmetry:** \( x = -2 \)
- **Width:** Since \(|a| = \frac{1}{2} < 1\), the parabola is **wider** than the standard \( y = x^2 \).
- **Sketching Steps:**
1. Plot the vertex at \( (-2, 2) \).
2. Draw the axis of symmetry \( x = -2 \).
3. Choose points on either side (e.g., \( x = -3 \) and \( x = -1 \)) and calculate \( y \)-values.
4. Plot these points and sketch the upward-opening, wider parabola.
---
### **e) \( m(x) = -(x + 2)^2 - 1 \)**
- **Vertex Form Analysis:**
- \( a = -1 \) (negative, so parabola opens **downwards**)
- \( h = -2 \)
- \( k = -1 \)
- **Vertex:** \( (-2, -1) \)
- **Axis of Symmetry:** \( x = -2 \)
- **Width:** Standard width since \(|a| = 1\).
- **Sketching Steps:**
1. Plot the vertex at \( (-2, -1) \).
2. Draw the axis of symmetry \( x = -2 \).
3. Select points around the vertex (e.g., \( x = -3 \) and \( x = -1 \)) to find \( y \)-values.
4. Plot these points and draw the downward-opening parabola.
---
### **f) \( f(x) = (x + 3)^2 - 4 \)**
- **Vertex Form Analysis:**
- \( a = 1 \) (positive, so parabola opens **upwards**)
- \( h = -3 \)
- \( k = -4 \)
- **Vertex:** \( (-3, -4) \)
- **Axis of Symmetry:** \( x = -3 \)
- **Width:** Standard width since \(|a| = 1\).
- **Sketching Steps:**
1. Plot the vertex at \( (-3, -4) \).
2. Draw the axis of symmetry \( x = -3 \).
3. Choose points on either side of the vertex (e.g., \( x = -4 \) and \( x = -2 \)) to determine \( y \)-values.
4. Plot these points and sketch the upward-opening parabola.
---
### **General Tips for Sketching Parabolas:**
1. **Identify the Vertex:** Locate the point \((h, k)\) where the parabola changes direction.
2. **Determine the Direction:**
- If \( a > 0 \), the parabola opens **upwards**.
- If \( a < 0 \), it opens **downwards**.
3. **Axis of Symmetry:** Draw a vertical line through the vertex at \( x = h \).
4. **Width of the Parabola:**
- \(|a| > 1\): **Narrower** than the standard parabola.
- \(|a| < 1\): **Wider** than the standard parabola.
- \(|a| = 1\): **Standard** width.
5. **Plot Additional Points:** Choose \( x \)-values on either side of the vertex to find corresponding \( y \)-values. This helps in accurately drawing the shape.
6. **Draw the Parabola:** Use the vertex, axis of symmetry, and plotted points to sketch the U-shaped curve.
By following these steps for each function, you can accurately sketch all the given parabolas. If you have graph paper or a graphing tool, it can greatly assist in visualizing these functions.
Reviewed and approved by the UpStudy tutoring team
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