i need help on 18a please!

Answer:
The answer to your question is below
Step-by-step explanation:
Data
f(x) = x² -1
g(x) = x² - 2
Process
1.- Substitute g(x) in f(x)
(f o g) (x) = (x² - 2)² - 1
2.- Expand the perfect square trinomial
(f o g) (x) = x⁴ - 4x² + 4 - 1
3.- Simplify
(f o g) (x) = x⁴ - 4x² + 3
4.- Conclusion
Following this process it was shown that (f o g)(x) = x⁴ - 4x² + 3