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The quadratic function \( y = -2x^{2} + 3x - 5 \) is a downward-opening parabola with its vertex at \( \left( \frac{3}{4}, -\frac{31}{8} \right) \). It has no real x-intercepts and its y-intercept is at \( (0, -5) \).
Solución
Certainly! Let's analyze the quadratic function provided:
\[ y = -2x^{2} + 3x - 5 \]
This is a quadratic equation of the form \( y = ax^{2} + bx + c \), where:
- \( a = -2 \)
- \( b = 3 \)
- \( c = -5 \)
### 1. **Direction of the Parabola**
Since \( a = -2 \) is negative, the parabola opens **downward**.
### 2. **Vertex of the Parabola**
The vertex form of a quadratic equation is:
\[ y = a(x - h)^2 + k \]
Where \((h, k)\) is the vertex.
To find the vertex, we can use the formula:
\[ h = -\frac{b}{2a} \]
\[ k = y(h) \]
**Calculating \( h \):**
\[ h = -\frac{b}{2a} = -\frac{3}{2(-2)} = -\frac{3}{-4} = \frac{3}{4} \]
**Calculating \( k \):**
\[ k = -2\left(\frac{3}{4}\right)^2 + 3\left(\frac{3}{4}\right) - 5 \]
\[ k = -2\left(\frac{9}{16}\right) + \frac{9}{4} - 5 \]
\[ k = -\frac{18}{16} + \frac{36}{16} - \frac{80}{16} \]
\[ k = \left(-18 + 36 - 80\right) \div 16 \]
\[ k = -62 \div 16 \]
\[ k = -\frac{31}{8} \]
**Vertex Coordinates:**
\[ \left( \frac{3}{4}, -\frac{31}{8} \right) \]
### 3. **Axis of Symmetry**
The axis of symmetry is the vertical line that passes through the vertex:
\[ x = h = \frac{3}{4} \]
### 4. **Y-intercept**
The y-intercept occurs where \( x = 0 \):
\[ y = -2(0)^2 + 3(0) - 5 = -5 \]
**Y-intercept: \( (0, -5) \)**
### 5. **X-intercepts (Roots)**
To find the x-intercepts, set \( y = 0 \) and solve for \( x \):
\[ 0 = -2x^{2} + 3x - 5 \]
This is a quadratic equation of the form \( ax^2 + bx + c = 0 \). We can use the quadratic formula:
\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]
**Calculating the discriminant (\( \Delta \)):**
\[ \Delta = b^2 - 4ac = 3^2 - 4(-2)(-5) = 9 - 40 = -31 \]
Since the discriminant is negative (\( \Delta < 0 \)), there are **no real x-intercepts**. Instead, the roots are complex.
**Complex Roots:**
\[ x = \frac{-3 \pm \sqrt{-31}}{-4} = \frac{-3 \pm i\sqrt{31}}{-4} = \frac{3}{4} \mp \frac{i\sqrt{31}}{4} \]
### 6. **Plotting the Parabola**
Given the above information:
- **Vertex:** \( \left( \frac{3}{4}, -\frac{31}{8} \right) \)
- **Axis of Symmetry:** \( x = \frac{3}{4} \)
- **Y-intercept:** \( (0, -5) \)
- **No Real X-intercepts**
- **Opens Downward**
The parabola will have its highest point at the vertex and will not cross the x-axis.
### 7. **Summary of Key Features**
- **Standard Form:** \( y = -2x^{2} + 3x - 5 \)
- **Vertex:** \( \left( \frac{3}{4}, -\frac{31}{8} \right) \)
- **Axis of Symmetry:** \( x = \frac{3}{4} \)
- **Direction:** Opens downward
- **Y-intercept:** \( (0, -5) \)
- **X-intercepts:** None (Complex roots)
If you have a specific question or need further analysis related to this quadratic function, feel free to ask!
Revisado y aprobado por el equipo de tutoría de UpStudy
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