The given function is:
\[
f(x) = \frac{1}{(x-2)(x-5)}
\]
For the function to be defined, the denominator must not be zero. So, we solve:
\[
(x-2)(x-5) \neq 0
\]
This implies:
\[
x \neq 2 \quad \text{and} \quad x \neq 5
\]
Thus, the domain of the function is all real numbers except \( x = 2 \) and \( x = 5 \).
The domain is:
\[
(-\infty, 2) \cup (5, \infty)
\]