Chapter 11 - Rational Expressions and Functions - 11-1 Simplifying Rational Expressions - Practice and Problem-Solving Exercises - Page 668: 31

$\frac{(2r−1)}{(r+5)}$ The denominator is zero when r=-5.

Converting numerator and denominator from quadratic equation into a product of two linear equations, we get $\frac{(2r−1)(r+5)}{(r+5)(r+5)}$, and upon simplifying, we get $\frac{(2r−1)}{(r+5)}$, The denominator is zero when r=-5.