Remember that the domain is the set of all the x terms.
So in the graph shown here, notice that the x terms seem to be increasing in both a positive and negative direction and there seems to be no limit to how large or how small the x terms can get. So the x terms can be all positive and negative numbers, including decimals and fractions.
In other words, the x terms can be All Real Numbers.
So the domain is equal to the set of all real numbers or R.
The range is the set of all the y terms.
Notice that all the y terms are less than or equal to 9.
So the range is {y: y ≤ 9}.