Finding the Domain of a Function

Find the domain of the function $f (x) = x^{2} - 1.$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
The input value, shown by the variable $x$ in the equation, is squared and then the result is lowered by one. Any real number may be squared and then be lowered by one, so there are no restrictions on the domain of this function. The domain is the set of real numbers.
In interval form, the domain of $f$ is $(- \infty, \infty) .$

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Find the domain of the function: $f (x) = 5 - x + x^{3} .$

How did it go?