If : A→B and g : B →C be two functions. Then, composition of f and g, gof : A→C is defined as
(gof)(x) = f(x), for all x ∈ A
(gof)(x) = g(f(x)), for all x ∈ A
(gof)(x) = f(g(x)), for all x ∈ A
(gof)(x) = g(x), for all x ∈ A
By definition, composition of f and g, gof is defined as (gof)(x) = g(f(x)), for all x ϵ A.