Determine the domain and range of the relation {(3, 8), (3, 2), (5, 2), (6, 1), (9,1)} I don't understood domain and range. Help please.

Astudent draws two parabolas both parabolas cross the x axis at (-4,0) and (6,0) the y intercept of the first parabolas is (0,-12). the y intercept of the second parabola is (0,-24) what is the positive difference between the a values for the two functions that describe the parabolas