The graphs of positive and negative x^2 parabolas will always have a domain of all real numbers. Even though you only have a portion of the graph and see a "restriction" on your domain values, it is incorrect to assume that the domain is limited to what you can see. As the branches of the parabola keep going up and up and up, the values of x keep getting bigger and bigger and bigger. Again, this is true for all + or - parabolas. ....... Can consider brainlist*:)
I believe that it is All Real Numbers because it is asking for the domain of function f, which is referring to the x axis only. If you were to graph that as an inequality, you’d come to the conclusion that the line could extend to all possible numbers on the x-axis.
