To start, the domain of a function is the set of x values a function has, in other words, the values the function has on the x-axis.
In this function, the graph appears to have a function going on infinitely in both directions (left and right). Because of this, your domain in interval notation would be (-∞,∞)
**Your interval notation would be in parenthesis because you cannot include negative or positive infinity as one of your values since while your graph is approaching these values, it never really reaches it.
