These expressions are called perfect square trinomials because:
they have three terms (TRINOMIAL)
VISUALLY: they can be arranged into a square (with equal width and length sides)
ALGEBRAICALLY: they can be re-written as a binomial squared ( __ + __ )2 (hence a PERFECT SQUARE)
Since Perfect Square Trinomials are easy to rewrite, it is helpful to know how to CREATE them!
Let's say that we're given x2 + 12x + ____. What value will COMPLETE THE SQUARE?
(How many 1's do we need to add?)