1. **State the problem:** Solve the quadratic equation $$-\frac{\sqrt{7}}{2}x^2 - 7x - \sqrt{7} = 0$$.
2. **Identify coefficients:** The quadratic equation is in the form $$ax^2 + bx + c = 0$$ where:
$$a = -\frac{\sqrt{7}}{2}, \quad b = -7, \quad c = -\sqrt{7}$$.
3. **Use the quadratic formula:**
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
4. **Calculate the discriminant:**
$$b^2 - 4ac = (-7)^2 - 4 \times \left(-\frac{\sqrt{7}}{2}\right) \times (-\sqrt{7}) = 49 - 4 \times \left(-\frac{\sqrt{7}}{2}\right) \times (-\sqrt{7})$$
5. Simplify the product inside the discriminant:
$$4 \times \left(-\frac{\sqrt{7}}{2}\right) \times (-\sqrt{7}) = 4 \times \frac{\sqrt{7}}{2} \times \sqrt{7} = 4 \times \frac{7}{2} = 14$$
6. Substitute back:
$$b^2 - 4ac = 49 - 14 = 35$$
7. **Calculate the roots:**
$$x = \frac{-(-7) \pm \sqrt{35}}{2 \times \left(-\frac{\sqrt{7}}{2}\right)} = \frac{7 \pm \sqrt{35}}{-\sqrt{7}}$$
8. Simplify the denominator:
$$2 \times \left(-\frac{\sqrt{7}}{2}\right) = -\sqrt{7}$$
9. Rewrite the expression:
$$x = \frac{7 \pm \sqrt{35}}{-\sqrt{7}} = -\frac{7 \pm \sqrt{35}}{\sqrt{7}}$$
10. Rationalize the denominator:
$$x = -\frac{7 \pm \sqrt{35}}{\sqrt{7}} \times \frac{\sqrt{7}}{\sqrt{7}} = -\frac{7\sqrt{7} \pm \sqrt{35} \sqrt{7}}{7}$$
11. Simplify the numerator:
$$\sqrt{35} \sqrt{7} = \sqrt{35 \times 7} = \sqrt{245} = 7\sqrt{5}$$
12. So,
$$x = -\frac{7\sqrt{7} \pm 7\sqrt{5}}{7} = -\left(\sqrt{7} \pm \sqrt{5}\right)$$
13. **Final solutions:**
$$x = -\sqrt{7} - \sqrt{5} \quad \text{or} \quad x = -\sqrt{7} + \sqrt{5}$$
Quadratic Roots B00409
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