Solve Quadratic 97A9Be
1. **State the problem:** Solve the equation $$x^2 - 4 = 15x (x - 1)$$ for $x$.
2. **Rewrite the equation:** Expand the right side:
$$x^2 - 4 = 15x^2 - 15x$$
3. **Bring all terms to one side:**
$$x^2 - 4 - 15x^2 + 15x = 0$$
4. **Combine like terms:**
$$-14x^2 + 15x - 4 = 0$$
5. **Multiply both sides by $-1$ to simplify:**
$$14x^2 - 15x + 4 = 0$$
6. **Use the quadratic formula:**
For $ax^2 + bx + c = 0$, solutions are
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
Here, $a=14$, $b=-15$, $c=4$.
7. **Calculate the discriminant:**
$$\Delta = (-15)^2 - 4 \times 14 \times 4 = 225 - 224 = 1$$
8. **Find the roots:**
$$x = \frac{15 \pm \sqrt{1}}{2 \times 14} = \frac{15 \pm 1}{28}$$
9. **Evaluate each root:**
- $$x_1 = \frac{15 + 1}{28} = \frac{16}{28} = \frac{4}{7}$$
- $$x_2 = \frac{15 - 1}{28} = \frac{14}{28} = \frac{1}{2}$$
**Final answer:** The solutions to the equation are $$x = \frac{4}{7}$$ and $$x = \frac{1}{2}$$.