Find the Excluded Values (x^2-81)/(8x+9)

$\frac{x^{2} - 81}{8 x + 9}$

Set the denominator in $\frac{x^{2} - 81}{8 x + 9}$ equal to $0$ to find where the expression is undefined.

$8 x + 9 = 0$

Solve for $x$ .

Subtract $9$ from both sides of the equation.

$8 x = - 9$

Divide each term in $8 x = - 9$ by $8$ and simplify.

Divide each term in $8 x = - 9$ by $8$ .

$\frac{8 x}{8} = \frac{- 9}{8}$

Simplify the left side.

Cancel the common factor of $8$ .

Cancel the common factor.

$\frac{8 x}{8} = \frac{- 9}{8}$

Divide $x$ by $1$ .

$x = \frac{- 9}{8}$

Simplify the right side.

Move the negative in front of the fraction.

$x = - \frac{9}{8}$