Given that the general equation of a quadratic equation is given as ax^2 + bx + c = 0, to complete the square, we subtract c from both sides of the equation and add the square of (b/2a) to both sides.Hence given x^2-5x-19=0, to complete the square, we add (-5/2)^2 to both sides following the illustration given.This is 25/4 or 6.24
