Solve the equation by completing the square. x^2 - 2x = 15

x = - 3 or x = 5

Step-by-step explanation:

Solve: x^2 - 2x = 15

x^2 - 2x - 15 = 0

Use the Diamond method of factoring

-15 = 3 * - 5 and 3 - 5 = - 2 so ...

x^2 - 2x - 15 = x^2 - 5x + 3x - 15

x^2 - 2x - 15 = x * (x - 5) + 3 * (x - 5)

x^2 - 2x - 15 = (x + 3) * (x - 5)

x^2 - 2x - 15 = (x + 3) * (x - 5) = 0

solve (x + 3) = 0 and (x - 5) = 0

x = - 3 or x = 5