Answer
not factorable
Work Step by Step
$\bf{\text{Solution Outline:}}$
The given expression, $
x^2-y^2-4
,$ is prime.
$\bf{\text{Solution Details:}}$
The given trinomial is not in the form $ax^2+bx+c,$ that can possibly be factored. It cannot also be grouped so that a $GCF\ne1$ can be factored. Hence, the given expression is $\text{
not factorable
.}$
