Answer
$(x+8)(x+9)$
Work Step by Step
We need to factor:
$x^2+17x+72$
The first term in each binomial must be $x$, since $x^2$ has no coefficient.
The operation in each binomial must be addition, since each term in the trinomial is positive.
Since $9+8=17$ and $9×8=72$, the other two terms are $9$ and $8$.
Thus, we have:
$x^2+17x+72=(x+8)(x+9)$
