## Algebra 1: Common Core (15th Edition)

$(v+9)(v-4)$
To factor a trinomial in the form $v^2+bv+c$, we must find two numbers whose product is $c$ and whose sum is $b$. We then insert these two numbers into the blanks of the factors $(v+\_)(v+\_)$. In the case of $v^2+5v-36$, we are looking for two numbers whose product is $-36$ and whose sum is $5$. The numbers $9$ and $-4$ meet these criteria because: $$9\times(-4)=-36\;\text{and}\;9+(-4)=5$$When we insert these numbers into the blanks, we arrive at the factors: $(v+9)(v-4)$.