# Does completing the square always work?

In order to use the Completing the Square method, the value for $a$ in the quadratic equation must be $1$. If it is not $1$, you will have to use the AC method or the quadratic formula in order to solve for $x$.
Completing the square is a method used to solve a quadratic equation, $a {x}^{2} + b x + c$, where $a$ must be $1$. The goal is to force a perfect square trinomial on one side and then solving for $x$ by taking the square root of both sides.