## Algebra 2 Common Core

$-(x+3)^2$
Factoring the $-1,$ the given expression, $-x^2-6x-9 ,$ is equivalent to \begin{align*}\require{cancel} & -(x^2+6x+9) .\end{align*} Using the factoring of trinomials in the form $x^2+bx+c,$ the trinomial expression above has $c= 9$ and $b= 6 .$ The two numbers with a product of $c$ and a sum of $b$ are $\left\{ 3,3 \right\}.$ Using these two numbers, the factored form of the expression above is \begin{align*} & -(x+3)(x+3) \\&= -(x+3)^2 .\end{align*} Hence, the factored form of the given expression is $-(x+3)^2$.