Responder
The quadratic function \( y = 4x^{2} + 8x + 2 \) has a vertex at \( (-1, -2) \), opens upwards, and intersects the y-axis at \( (0, 2) \). It also crosses the x-axis at approximately \( (-0.293, 0) \) and \( (-1.707, 0) \).
Solución
Certainly! Let's analyze the quadratic function \( y = 4x^{2} + 8x + 2 \). We'll explore its key features, including its vertex, intercepts, axis of symmetry, and graph characteristics.
## 1. **Standard Form**
The given quadratic function is in the standard form:
\[ y = ax^{2} + bx + c \]
where:
- \( a = 4 \)
- \( b = 8 \)
- \( c = 2 \)
## 2. **Vertex**
The vertex of a parabola described by a quadratic function can be found using the formulas:
\[ x_{\text{vertex}} = -\frac{b}{2a} \]
\[ y_{\text{vertex}} = f(x_{\text{vertex}}) \]
Calculating the \( x \)-coordinate:
\[ x_{\text{vertex}} = -\frac{8}{2 \times 4} = -\frac{8}{8} = -1 \]
Substituting \( x = -1 \) into the original equation to find \( y \):
\[ y_{\text{vertex}} = 4(-1)^2 + 8(-1) + 2 = 4(1) - 8 + 2 = 4 - 8 + 2 = -2 \]
**Vertex:** \( (-1, -2) \)
## 3. **Axis of Symmetry**
The axis of symmetry is a vertical line that passes through the vertex:
\[ x = -1 \]
## 4. **Y-Intercept**
The y-intercept occurs when \( x = 0 \):
\[ y = 4(0)^2 + 8(0) + 2 = 0 + 0 + 2 = 2 \]
**Y-Intercept:** \( (0, 2) \)
## 5. **X-Intercepts (Roots)**
To find the x-intercepts, set \( y = 0 \) and solve for \( x \):
\[ 0 = 4x^{2} + 8x + 2 \]
Using the quadratic formula:
\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
\[ x = \frac{-8 \pm \sqrt{8^2 - 4 \times 4 \times 2}}{2 \times 4} \]
\[ x = \frac{-8 \pm \sqrt{64 - 32}}{8} \]
\[ x = \frac{-8 \pm \sqrt{32}}{8} \]
\[ x = \frac{-8 \pm 4\sqrt{2}}{8} \]
\[ x = \frac{-2 \pm \sqrt{2}}{2} \]
**Approximate X-Intercepts:**
- \( x \approx \frac{-2 + 1.414}{2} \approx -0.293 \)
- \( x \approx \frac{-2 - 1.414}{2} \approx -1.707 \)
So, the x-intercepts are approximately \( (-0.293, 0) \) and \( (-1.707, 0) \).
## 6. **Direction of Opening**
Since the coefficient of \( x^2 \) (which is 4) is positive, the parabola opens **upwards**.
## 7. **Graph Sketch**
Here's a summary of the key features to plot the graph:
- **Vertex:** \( (-1, -2) \)
- **Axis of Symmetry:** \( x = -1 \)
- **Y-Intercept:** \( (0, 2) \)
- **X-Intercepts:** Approximately \( (-0.293, 0) \) and \( (-1.707, 0) \)
- **Opening:** Upwards
**Steps to Sketch:**
1. Plot the vertex at \( (-1, -2) \).
2. Draw the axis of symmetry as a dashed vertical line through \( x = -1 \).
3. Plot the y-intercept at \( (0, 2) \).
4. Plot the x-intercepts at approximately \( (-0.293, 0) \) and \( (-1.707, 0) \).
5. Since the parabola is symmetric, plot another point on the opposite side of the axis of symmetry for each x-intercept (e.g., reflect the y-intercept across the axis).
6. Draw a smooth curve through these points, opening upwards.
**Graph Illustration:**
While I can't provide a visual graph here, you can use graphing tools like Desmos or GeoGebra to input the function \( y = 4x^{2} + 8x + 2 \) and visualize the parabola with the features described above.
## 8. **Additional Features**
- **Minimum Value:** Since the parabola opens upwards, the vertex represents the minimum point of the function. Therefore, the minimum value of \( y \) is **-2**, occurring at \( x = -1 \).
- **Range:** \( y \geq -2 \)
- **Domain:** All real numbers (\( -\infty < x < \infty \))
## 9. **Summary**
- **Vertex:** \( (-1, -2) \)
- **Axis of Symmetry:** \( x = -1 \)
- **Y-Intercept:** \( (0, 2) \)
- **X-Intercepts:** Approximately \( (-0.293, 0) \) and \( (-1.707, 0) \)
- **Direction:** Opens upwards
- **Minimum Value:** \( y = -2 \) at \( x = -1 \)
- **Range:** \( y \geq -2 \)
- **Domain:** All real numbers
Feel free to ask if you need further clarification or additional information about this quadratic function!
Revisado y aprobado por el equipo de tutoría de UpStudy
Explicar
Simplifique esta solución