In this case, we'll have to carry out several steps to find the solution.
Step 01:
data:
f(x)= -3x³ - 8x² - x + 8
g(x)= 3x³ - 6x² - 8x - 8
Step 02:
functions:
(f - g)(x):
(f - g)(x) = -3x³ - 8x² - x + 8 - (3x³ - 6x² - 8x - 8)
(f - g)(x) = -3x³ - 8x² - x + 8 - 3x³ + 6x² + 8x + 8
(f - g)(x) = - 6x³ - 2x² + 7x + 16
(f - g)(-1):
(f - g)(-1) = - 6(-1)³ - 2(-1)² + 7(-1) + 16
(f - g)(-1) = - 6(-1) - 2(1) + 7(-1) + 16
(f - g)(-1) = 6 - 2 - 7 + 16
(f - g)(-1) = 13
That is the full solution.