## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Using the factoring of trinomials in the form $x^2+bx+c,$ the $\text{ expression }$ \begin{array}{l}\require{cancel} x^2-2x-5 \end{array} has $c= -5$ and $b= -2 .$ There are no two numbers with a product of $c$ and a sum of $b.$ Hence, the given expression is not factorable or is $\text{ prime .}$