Let f : {3, 9, 12} {1, 3, 4} and g : {1, 3, 4, 5} {3, 9} be

defined as f = {(3, 1), (9, 3), (12, 4)} and


g = {(1, 3), (3, 3), (4, 9), (5, 9)}.


Find (i) (g o f) (ii) (f o g).


(i) g o f


To find: g o f


Formula used: g o f = g(f(x))


Given: f = {(3, 1), (9, 3), (12, 4)} and g = {(1, 3), (3, 3),(4, 9), (5, 9)}


Solution: We have,


gof(3) = g(f(3)) = g(1) = 3


gof(9) = g(f(9)) = g(3) = 3


gof(12) = g(f(12)) = g(4) = 9


Ans) g o f = {(3, 3), (9, 3), (12, 9)}


(ii) f o g


To find: f o g


Formula used: f o g = f(g(x))


Given: f = {(3, 1), (9, 3), (12, 4)} and g = {(1, 3), (3, 3),(4, 9), (5, 9)}


Solution: We have,


fog(1) = f(g(1)) = f(3) = 1


fog(3) = f(g(3)) = f(3) = 1


fog(4) = f(g(4)) = f(9) = 3


fog(5) = f(g(5)) = f(9) = 3


Ans) f o g = {(1, 1), (3, 1), (4, 3), (5, 3)}


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