1. **State the problem:** Solve the equation $$25(x + 2)^2 = (x - 7)^2 - 81$$ for $x$.
2. **Rewrite the equation:** Expand both sides.
$$25(x + 2)^2 = (x - 7)^2 - 81$$
3. **Expand the squares:**
$$25(x^2 + 4x + 4) = (x^2 - 14x + 49) - 81$$
4. **Distribute:**
$$25x^2 + 100x + 100 = x^2 - 14x + 49 - 81$$
5. **Simplify the right side:**
$$x^2 - 14x - 32$$
6. **Bring all terms to one side:**
$$25x^2 + 100x + 100 - x^2 + 14x + 32 = 0$$
7. **Combine like terms:**
$$24x^2 + 114x + 132 = 0$$
8. **Simplify by dividing all terms by 6:**
$$\cancel{6}4x^2 + \cancel{6}19x + \cancel{6}22 = 0$$
9. **Use the quadratic formula:**
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$$
where $a=4$, $b=19$, $c=22$.
10. **Calculate the discriminant:**
$$\Delta = 19^2 - 4 \times 4 \times 22 = 361 - 352 = 9$$
11. **Find the roots:**
$$x = \frac{-19 \pm \sqrt{9}}{2 \times 4} = \frac{-19 \pm 3}{8}$$
12. **Calculate each solution:**
$$x_1 = \frac{-19 + 3}{8} = \frac{-16}{8} = -2$$
$$x_2 = \frac{-19 - 3}{8} = \frac{-22}{8} = -\frac{11}{4}$$
**Final answer:**
$$x = -2 \quad \text{or} \quad x = -\frac{11}{4}$$
Quadratic Equation 9A791A
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