Hello!
The given equation can be rewritten to read as follows:
(f · g)(x) = f(g(x))
In other words, insert the given value of g(x) in place of the variable found in f(x) as follows:
f(5x² – 3) = 2(5x² – 3) – 2
Now simplify the right side of the equation:
f(5x² – 3) = 10x² – 6 – 2
Combine like terms:
f(5x² – 3) = 10x² – 8
We have now proven that (f · g)(x) is equal to 10x² – 8.
I hope this helps!