#### Answer

a. {$x$|$x$ is a real number}
b. $(-∞,∞)$

#### Work Step by Step

We are given the function $f(x)=\frac{x-9}{26}$. The domain of the function will be all values of $x$ such that the denominator does not equal 0.
Therefore, we can set the denominator equal to 0. We will exclude from the domain all values of $x$ that make the denominator equal 0.
$26=0$
This is not a true statement, so we know that the domain includes all real numbers.
Therefore, the domain is {$x$|$x$ is a real number} in set-builder notation and $(-∞,∞)$ in interval notation.