Responder
The axis of symmetry for the parabola \( f(x) = -2x^{2} + 5 \) is \( x = 0 \).
Solución
To graph the parabola \( f(x) = -2x^{2} + 5 \) and identify its **axis of symmetry**, follow these steps:
### 1. **Understanding the Parabola**
The given quadratic function is in the form:
\[ f(x) = ax^{2} + bx + c \]
where:
- \( a = -2 \)
- \( b = 0 \) (since there's no \( x \) term)
- \( c = 5 \)
Since \( a = -2 \) is negative, the parabola opens **downwards**.
### 2. **Finding the Vertex**
The vertex of a parabola \( f(x) = ax^{2} + bx + c \) is given by:
\[ \text{Vertex } (h, k) \]
where:
\[ h = -\frac{b}{2a} \]
\[ k = f(h) \]
For our function:
\[ h = -\frac{0}{2(-2)} = 0 \]
\[ k = f(0) = -2(0)^2 + 5 = 5 \]
**Vertex:** \( (0, 5) \)
### 3. **Determining the Axis of Symmetry**
The **axis of symmetry** of a parabola is a vertical line that passes through the vertex. Its equation is:
\[ x = h \]
For our vertex \( (0, 5) \):
\[ \text{Axis of Symmetry: } x = 0 \]
### 4. **Plotting the Parabola**
1. **Vertex:** Plot the vertex at \( (0, 5) \).
2. **Axis of Symmetry:** Draw a dashed vertical line through the vertex along \( x = 0 \).
3. **Additional Points:**
- Choose values for \( x \) on either side of the axis of symmetry to find corresponding \( y \)-values.
For example:
| \( x \) | \( f(x) = -2x^{2} + 5 \) |
|-------|--------------------------|
| -2 | \( -2(-2)^2 + 5 = -8 + 5 = -3 \) |
| -1 | \( -2(-1)^2 + 5 = -2 + 5 = 3 \) |
| 0 | \( 5 \) (vertex) |
| 1 | \( -2(1)^2 + 5 = -2 + 5 = 3 \) |
| 2 | \( -2(2)^2 + 5 = -8 + 5 = -3 \) |
4. **Symmetry:** Plot these points on both sides of the axis of symmetry to maintain symmetry.
5. **Shape:** Connect the points with a smooth, U-shaped curve opening downwards.
### 5. **Graph Illustration**
While I can't provide a visual graph here, here's a description of how it would look:
- **Vertex:** Highest point at (0, 5).
- **Axis of Symmetry:** A vertical dashed line along \( x = 0 \).
- **Points:**
- Left of the vertex: (-2, -3) and (-1, 3).
- Right of the vertex: (1, 3) and (2, -3).
- **Parabola Shape:** Downward-facing "U" passing through these points.
### 6. **Summary**
- **Axis of Symmetry:** \( x = 0 \)
- **Vertex:** \( (0, 5) \)
- **Direction:** Opens downward.
### 7. **Final Answer**
After graphing \( f(x) = -2x^{2} + 5 \), the **axis of symmetry** is the vertical line:
\[
\boxed{x = 0}
\]
Respondido por UpStudy AI y revisado por un tutor profesional
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