Answer:
27x^2 - 159x + 223
Step-by-step explanation:
We replace the x in f(x) by g(x):
f(g(x)) = 3(3x - 8)^2 - 5(3x - 8) - 9
= 3(9x^2 - 48x + 64) - 15x + 40 - 9
= 27x^2 - 144x + 192 - 15x + 31
= 27x^2 - 159x + 223.
