Answer
not factorable
Work Step by Step
$a^2+a-3$
There are an infinite number of pairs whose sum is 1. However, there are only two pairs of numbers whose product is $-3$: $1$ and $-3$, and $-1$ and $3$.
$1-3=-2$
$-1+3=2$
Neither pair of numbers has a sum of 1, so this polynomial cannot be factored using just integers.