## Algebra: A Combined Approach (4th Edition)

This expression is undefined for $x=2$ and for $x=-2$
$\dfrac{x+5}{x^{2}-4}$ 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 $x=-2$