Some quadratics cannot be factorised. An alternative method to solve a quadratic equation is to complete the square. To solve an equation of the form \(x^2 + bx + c = 0\) consider the expression ...

Rewrite \(y = {x^2} - 6x + 11\) in the form \(y = {(x - b)^2} + c\). To get \(b\) (the number inside the bracket), halve the coefficient (number in front) of the second term in the original equation.