Answer:
f(3x + 1) = - 18x - 5
Step-by-step explanation:
Substitute x = 3x + 1 into f(x), that is
f(3x + 1)
= - 6(3x + 1) + 1 ← distribute and simplify
= - 18x - 6 + 1
= - 18x - 5
