Let $\displaystyle {f{{\left({x}\right)}}}={\frac{{{1}}}{{{x}-{8}}}}$ and $\displaystyle {g{{\left({x}\right)}}}={\frac{{{1}}}{{{x}-{9}}}}$.
Then the domain of $\displaystyle {f}\circ{g}$ is equal to all reals except for two values, $\displaystyle {a}$ and $\displaystyle {b}$ with $\displaystyle {a}<{b}$ and
$\displaystyle {a}=$ Preview Question 6 Part 1 of 2  
$\displaystyle {b}=$ Preview Question 6 Part 2 of 2