Question

Let f and g be two functions given by f = {(2, 4), (5, 6), (8, -1), (10, -3)} and g = {(2, 5), (7, 1), (8, 4), (10, 13), (11, -5)}
Find the domain of f + g.

Answer 1

f = {(2, 4), (5, 6), (8, -1), (10, -3)}
g = {(2, 5), (7, 1), (8, 4), (10, 13), (11, -5)}
(f + g) (2) = f(2) + g(2) = 4 + 5 = 9
(f + g) (8) = f(8) + g(8) = -1 + 4 = 3
(f + g) (10) = f(10) + g(10) = -3 + 13 = 10
$\therefore$ f + g = {(2, 9), (8, 3), (10, 10)}