# How to Solve a Quadratic Equation by Completing the Square

You can solve quadratic equations by *completing the square*. Completing the square involves creating a perfect square trinomial from the quadratic equation, and then solving that trinomial by taking its square root.

Put the

*x*-squared and the*x*terms on one side and the constant on the other side.Divide both sides by the coefficient of

*x*-squared (unless, of course, it’s 1).Take half of the coefficient of

*x,*square it, then add that to both sides.Factor the left side.

Notice that the factor always contains the same number you found in Step 3 (–4 in this example).

Take the square root of both sides.

Solve.