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h. \( y=4 x^{2}+8 x+2 \)

Ask by Pena Stewart. in South Africa
Jan 23,2025

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Answer

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 \( (-1.707, 0) \).

Solution

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!

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Mind Expander

Did you know that this is a quadratic equation, which means it forms a parabola when graphed? In this case, the parabola opens upwards because the coefficient of \( x^2 \) (which is 4) is positive. You can find the vertex of the parabola using the formula \( x = -\frac{b}{2a} \), where \( a = 4 \) and \( b = 8 \). This gives you the x-coordinate of the vertex, which is the minimum point on the graph. If you're looking to solve or graph this equation, keep an eye out for the common mistake of misidentifying the vertex! Remember that the vertex is not the same as the y-intercept. The y-intercept can be found simply by substituting \( x = 0 \) into the equation, leading you directly to the point (0, 2) on your graph!

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