Answer
This expression is undefined for $x=2$ and for $x=-2$
Work Step by Step
$\dfrac{x+5}{x^{2}-4}$
This rational expression is undefined for the values of $x$ that make the denominator equal to $0$. Knowing that, we just need to solve the equation $x^{2}-4=0$ to find those values:
$x^{2}-4=0$
Take the $-4$ to the right side of the equation:
$x^{2}=4$
Take the square root of both sides:
$\sqrt{x^{2}}=\sqrt{4}$
$x=\pm2$
This expression is undefined for $x=2$ and for $x=-2$