what is the domain of this quadratic function?

Explanation:

Step1: Recall domain definition

The domain of a function is the set of all possible input - values (x - values).

Step2: Analyze quadratic function graph

For a quadratic function, there are no restrictions on the x - values. The graph of a quadratic function extends infinitely to the left and right.

Answer:

All real numbers, or $(-\infty,\infty)$