what is the formula for completing the square method?
An alternative method to solve a quadratic equation is to complete the square. To solve an equation of the form x 2 + b x + c = 0 consider the expression ( x + b 2 ) 2 + c . ( x + b 2 ) 2 + c expands to x 2 + b x + ( b 2 ) 2 + c , which is the same as the left-hand side of the original equation but with an extra term.