Answer :
The function \( f(x) = 5x \) is a linear function, and there are no restrictions on the values that \( x \) can take. Therefore, the domain of the function is all real numbers.
In mathematical notation, the domain is:
\[ \text{Domain of } f(x) = 5x \text{ is } (-\infty, \infty). \]
In mathematical notation, the domain is:
\[ \text{Domain of } f(x) = 5x \text{ is } (-\infty, \infty). \]
