and g be two functions given by

It is given that f and g are two functions such that

f = {(2, 4), (5, 6), (8, −1), (10, −3)}

and g = {(2, 5), (7, 1), (8, 4), (10, 13), (11, −5)}

Now,

Domain of f = Df = {2, 5, 8, 10}

Domain of g = Dg = {2, 7, 8, 10, 11}

∴ Domain of f + g = Df ∩ Dg = {2, 8, 10}