Question

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

Answer 1

x = -3 or x = 5

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