diketahui f(x) = 6x - 3, g(x) = 5x + 4 dan (fog) (a) = 81. nilai a =...

jawab

f(x)= 6x - 3
g(x) =  5x + 4


fog(x) = f ( g(x) )
= f (5x + 4)
= 6(5x+ 4) - 3
= 30 x + 24 - 3
= 30 x + 21

f0g(a) = 81
30a + 21= 81
30 a = 60
a = 2