## Precalculus: Mathematics for Calculus, 7th Edition

$x^{2}+12x+36=(x+6)^{2}$
$x^{2}+12x+36$ This expression is a perfect square trinomial. To factor it, we just form a parentheses with the square root of the first term and the square root of the third term. Between them, we put the sign of second term in the trinomial and finally, we square the parentheses. $x^{2}+12x+36=(x+6)^{2}$