The natural domain of the function $f(x) = 7 - 3x$ includes all real values of $x$ for which the function is defined. Since this function is a linear expression with no restrictions such as square roots, logarithms, or divisions by zero, $f(x)$ is defined for all real numbers.

Therefore, the natural domain of $f(x) = 7 - 3x$ is:

$(-\infty, \infty)$

Would you like more details or have any questions?

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Here are five related questions that explore similar concepts:

1. What is the natural domain of $g(x) = \frac{5}{x - 2}$?
2. How do you find the domain of $h(x) = \sqrt{5 - x}$?
3. What is the domain of $k(x) = \ln(x + 1)$?
4. If $f(x) = 7 - 3x$, what is its range?
5. How would you determine the domain of a quadratic function, such as $f(x) = x^2 - 4x + 4$?

Tip: For functions with square roots, logarithms, or fractions, look out for domain restrictions where inputs can lead to undefined or non-real values.