1. **Problem statement:**
Solve the system of equations graphically:
$$y = 2x^2 - 3x - 7$$
and
$$y = 2x - 1$$
Also, find the minimum value of the quadratic function $$2x^2 - 3x - 7$$.
2. **Graphical method to solve the system:**
The solutions are the points where the parabola and the line intersect.
Set the two expressions for $$y$$ equal:
$$2x^2 - 3x - 7 = 2x - 1$$
3. **Rearrange the equation:**
$$2x^2 - 3x - 7 - 2x + 1 = 0$$
$$2x^2 - 5x - 6 = 0$$
4. **Solve the quadratic equation:**
Use the quadratic formula:
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $$a=2$$, $$b=-5$$, $$c=-6$$.
5. **Calculate the discriminant:**
$$\Delta = (-5)^2 - 4 \times 2 \times (-6) = 25 + 48 = 73$$
6. **Find the roots:**
$$x = \frac{5 \pm \sqrt{73}}{4}$$
7. **Approximate the roots:**
$$\sqrt{73} \approx 8.544$$
$$x_1 = \frac{5 + 8.544}{4} = \frac{13.544}{4} = 3.386$$
$$x_2 = \frac{5 - 8.544}{4} = \frac{-3.544}{4} = -0.886$$
8. **Find corresponding y-values:**
Use $$y = 2x - 1$$:
For $$x_1 = 3.386$$:
$$y_1 = 2(3.386) - 1 = 6.772 - 1 = 5.772$$
For $$x_2 = -0.886$$:
$$y_2 = 2(-0.886) - 1 = -1.772 - 1 = -2.772$$
9. **Solutions to the system:**
$$(3.386, 5.772)$$ and $$(-0.886, -2.772)$$
10. **Minimum value of $$2x^2 - 3x - 7$$:**
The quadratic opens upwards (since $$a=2>0$$), so minimum at vertex.
Vertex formula for $$x$$:
$$x = -\frac{b}{2a} = -\frac{-3}{2 \times 2} = \frac{3}{4} = 0.75$$
11. **Calculate minimum value:**
$$y = 2(0.75)^2 - 3(0.75) - 7 = 2(0.5625) - 2.25 - 7 = 1.125 - 2.25 - 7 = -8.125$$
**Final answers:**
- Intersection points: $$(3.386, 5.772)$$ and $$(-0.886, -2.772)$$
- Minimum value of $$2x^2 - 3x - 7$$ is $$-8.125$$ at $$x=0.75$$.
Graphical Solution Fa0Aaf
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.