Answer:
x ∈ R, x ≠ 9
Step-by-step explanation:
Given
f(x) = [tex]\frac{1}{x-9}[/tex]
The denominator of f(x) cannot be zero as this would make f(x) undefined.
To find the value that x cannot be, equate the denominator to zero and solve for x
x - 9 = 0 ⇒ x = 9 ← excluded value
Thus the domain is x ∈ R, x ≠ 9
