x^2 = 4x + 12
x^2 - 4x - 12 = 0, use the quadratic equation
Solve for x over the real numbers:
(x - 6) (x + 2) = 0
Split into two equations:
x - 6 = 0 or x + 2 = 0
Add 6 to both sides:
x = 6 or x + 2 = 0
Subtract 2 from both sides:
Answer: x = 6 (or x = -2 only positive solution)