Struggling a bit with this one and can't seem to find a tutorial for a specific equation like this. find the domain and range of the relation and determine whether it is a function. a. domain: all real numbers; range: all real numbers; yes, it is a function. b. domain: positive integers; range: positive integers; no, it is not a function. c. domain: x ≥ 0; range: y > 3; no, it is not a function. d. domain: x > 3; range: y > 0; yes, it is a function.