diketahui f(x)= 2x+5 dan g(x)= x-1/x+4, jika (fog)(a)=5 carilah nilai a

f(g(x)) = 2{(x-1)/(x+4)}+5
= (2x-2)/(x+4) + 5
= {(2x-2)+(5x+20)}/x+4
= 7x+18/x+4
f(g(a)) = 7a+18/a+4
5 = 7a+18/a+4
5a+20 = 7a+18
20-18 = 7a-5a
2a = 2
a = 1