## Intermediate Algebra (12th Edition)

$\bf{\text{Solution Outline:}}$ 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 $\text{ not factorable .}$