diketahui fungsi f(x)=6×-3dan g(×)=5×+4.jika (gof)(a)=81, maka nilai a adalah

(g o f )(x) = g(f(x))

g(x) = 5x + 4
g(f(x)) = g(6x - 3)
g(6x - 3) = 5(6x - 3) + 4
g(6x - 3) = 30x - 15 + 4
(g o f)(x) = 30x - 11

(g o f)(a) = 30a - 11
81 = 30a - 11
81 + 11 = 30a
99 = 30a
a = 99/30
a = 3,3