What is the domain and range of the function?
Domain:

Domain: {x∈R}

Range: {f(x)∈R | f(x) ≥ 0}

Step-by-step explanation:

The domain of a function is, in simple terms, all the possible x values of a function (input values), and as the graph shows that all x values are possible (x, 0 and -x) meaning x can be any rational number, represented by the R and the subset symbol (∈).

The range is all the possible f(x) values (outputs/y values) and if you look at the graph you see that it isn't possible for the f(x)/output/y values to be negative so we write:

{f{x}∈R (f(x)/output/y value is rational) | (and) f(x) ≥ 0 (f(x)/output/y value is bigger or equal to 0, not negative)}

Hope I helped :)

e.

step-by-step explanation:

because there are always 10 numbers in a phone number.