Final answer:
To evaluate (g-f)(8), substitute 8 into both g(x) and f(x), subtract f(8) from g(8), and simplify the result.
Step-by-step explanation:
To evaluate (g-f)(8), we need to substitute 8 into both g(x) and f(x) and then subtract the result of f(8) from g(8).
Using the given values of f(x) and g(x), we have:
g(8) = log4(8) = log423 = 3/2
f(8) = (8+3)/(8²-4(8)-21) = 11/9
Therefore, (g-f)(8) = g(8) - f(8) = 3/2 - 11/9 = (27-22)/18 = 5/18.