# Completing the Square

Algebra tiles are useful for this lesson. If you do not have algebra tiles to use, virtual algebra tiles can be found online.

**Completing the square**.

What expression is represented by the blue, green, and yellow algebra tiles below?

What would have to be added to make the diagram a complete square?

So, the expression before completing the square was \(x^2+4x+2\). After completing the square (adding 2), the new expression is \((x^2+4x+4)-2\) which when simplified is \((x+2)^2-2\).

Because two was added to the existing expression, to create a perfect square trinomial, two also has to be subtracted to have an equivalent expression.

Use the same process for the the diagram below.