1. Move 9 to the other side of the equation:
X^2 + 8X - 9 = 0
2. Factor the quadratic equation:
(X + 9)(X - 1) = 0
3. Apply the zero product property:
X + 9 = 0 \text{ or } X - 1 = 0
4. Solve for X:
X = -9 \text{ or } X = -1
Answer: X = -9 \text{ or } X = -1