Final answer:
To find (f+g)(x), add the given functions f(x) and g(x).
Step-by-step explanation:
To find (f+g)(x), we need to add the given functions f(x) and g(x).
(f+g)(x) = f(x) + g(x)
According to the given functions, f(x) = -5x² + 4x - 9 and g(x) = 8x² - 3x - 4.
Adding the two functions, we get:
(f+g)(x) = (-5x² + 4x - 9) + (8x² - 3x - 4)
= -5x² + 4x - 9 + 8x² - 3x - 4
= 3x² + x - 13