Step 1: Substitute \( x = -1 \) into the function \( f(x) = x^3 + 4x + 12 \):
\[
f(-1) = (-1)^3 + 4(-1) + 12
\]
Step 2: Simplify each term:
\[
f(-1) = -1 - 4 + 12
\]
Step 3: Add the terms:
\[
f(-1) = 7
\]
Thus, the value of the function when \( x = -1 \) is 7.