Quadratic Analysis 730666
1. **Problem:** Solve and analyze the quadratic equation $x^2 - 25 = 0$.
2. **Formula and rules:** The quadratic equation is $ax^2 + bx + c = 0$. The axis of symmetry is $x = -\frac{b}{2a}$, the vertex is at $(x, y)$ where $y = f(x)$, the y-intercept is $c$, and the x-intercepts are solutions to the equation.
3. **Solution:**
$$x^2 - 25 = 0 \Rightarrow x^2 = 25 \Rightarrow x = \pm 5$$
4. **Axis of symmetry:**
$$x = -\frac{0}{2 \times 1} = 0$$
5. **Vertex:**
$$y = (0)^2 - 25 = -25$$
Vertex = (0, -25)$$
6. **Y-intercept:**
$$y = -25$$
7. **X-intercepts:**
$$x = 5, -5$$
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1. **Problem:** Solve and analyze $-x^2 - 4x = 0$.
2. **Rewrite:**
$$-x^2 - 4x = 0 \Rightarrow x^2 + 4x = 0$$
3. **Factor:**
$$x(x + 4) = 0 \Rightarrow x = 0 \text{ or } x = -4$$
4. **Axis of symmetry:**
$$x = -\frac{4}{2 \times 1} = -2$$
5. **Vertex:**
$$y = -( -2)^2 - 4(-2) = -4 + 8 = 4$$
Vertex = (-2, 4)$$
6. **Y-intercept:**
$$y = 0$$
7. **X-intercepts:**
$$x = 0, -4$$
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1. **Problem:** Solve and analyze $-2x^2 + 5x + 6 = 0$.
2. **Use quadratic formula:**
$$a = -2, b = 5, c = 6$$
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{-5 \pm \sqrt{25 - 4(-2)(6)}}{2(-2)} = \frac{-5 \pm \sqrt{25 + 48}}{-4} = \frac{-5 \pm \sqrt{73}}{-4}$$
3. **Approximate roots:**
$$x_1 = \frac{-5 + 8.544}{-4} = \frac{3.544}{-4} = -0.886$$
$$x_2 = \frac{-5 - 8.544}{-4} = \frac{-13.544}{-4} = 3.386$$
4. **Axis of symmetry:**
$$x = -\frac{5}{2(-2)} = \frac{5}{4} = 1.25$$
5. **Vertex:**
$$y = -2(1.25)^2 + 5(1.25) + 6 = -2(1.5625) + 6.25 + 6 = -3.125 + 12.25 = 9.125$$
Vertex = (1.25, 9.125)$$
6. **Y-intercept:**
$$y = 6$$
7. **X-intercepts:**
$$x \approx -0.886, 3.386$$
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1. **Problem:** Solve and analyze $x^2 - 10x + 25 = 0$.
2. **Recognize perfect square:**
$$x^2 - 10x + 25 = (x - 5)^2 = 0$$
3. **Solution:**
$$x = 5$$
4. **Axis of symmetry:**
$$x = 5$$
5. **Vertex:**
$$y = 0$$
Vertex = (5, 0)$$
6. **Y-intercept:**
$$y = 25$$
7. **X-intercepts:**
$$x = 5$$
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1. **Problem:** Analyze $4x^2 + 5x + 20$ (no equation given, so analyze the function).
2. **Axis of symmetry:**
$$x = -\frac{5}{2 \times 4} = -\frac{5}{8} = -0.625$$
3. **Vertex:**
$$y = 4(-0.625)^2 + 5(-0.625) + 20 = 4(0.390625) - 3.125 + 20 = 1.5625 - 3.125 + 20 = 18.4375$$
Vertex = (-0.625, 18.4375)$$
4. **Y-intercept:**
$$y = 20$$
5. **X-intercepts:**
Use quadratic formula:
$$a=4, b=5, c=20$$
$$\Delta = 5^2 - 4(4)(20) = 25 - 320 = -295 < 0$$
No real x-intercepts.
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**Summary:**
- Each quadratic's axis of symmetry, vertex, y-intercept, and x-intercepts are found.
- Solutions for x-intercepts are shown using factoring or quadratic formula.
- Graphs are parabolas opening up or down depending on $a$.