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). Then, domain of f + g is __________ .

Answer 1

f = {(2, 4), (5, 6), (8, –1), (10, –3)}
g = {(2, 5), (7, 1), (8, 4), (10, 13), (11, –5)}
Domain of f is {2, 5, 8, 10} and Domain of g = {2, 7, 8, 10, 11}
Since (f + g) (x) = f(x) + g(x)
∴ x should lie in Both Domain of f and Domain of g
∴ x ∈ Domain ( f) ∩ Domain (g)
i.e Domain of f + g is {2, 8, 10}