Answer:
all real numbers: -∞ < x < ∞
Step-by-step explanation:
Any polynomial function is defined for all real numbers. This one is, too.
The domain is ...
-∞ < x < ∞
_____
Additional comment
Polynomial functions are often used to model things in the real world. One common application is the use of a quadratic function to model ballistic motion (height versus time). Such functions are defined for all values of the independent variable (time), but only have practical application over a smaller domain (time and height ≥ 0). Any question of domain might need to consider the practical domain, where the function is useful.
