Complete the square and find the roots of the quadratic equation x2 24x 0?

x^2 + 24x = 0 add to both sides 12^2 (144)

x^2 + 24x + 12^2 = 12^2 use the formula (a + b)^2 = a^2 + 2ab + b^2;

(x + 12)^2 = 12^2

x + 12 = +, - 12 subtract 12 to both sides;

x = 0 or x = -24