x2 − 225 = 0
This is a quadratic equation. To solve for x, we can use the difference of squares formula:
x^2 - 225 = (x + 15)(x - 15) = 0
So either (x + 15) = 0 or (x - 15) = 0. Solving for x gives us:
x = -15 or x = 15
Therefore, the solutions to the equation are x = -15 and x = 15.