Final answer:
To find (f+g)(x), substitute the functions f(x) = 5x and g(x) = 4x + 3 into (f+g)(x) and simplify the expression to get 9x + 3.
Step-by-step explanation:
To find (f+g)(x), we need to add the two functions f(x) and g(x). Given that f(x) = 5x and g(x) = 4x + 3, we can simply replace f(x) and g(x) in (f+g)(x) and perform the addition.
(f+g)(x) = f(x) + g(x) = (5x) + (4x + 3)
Simplifying, we combine like terms:
(f+g)(x) = 5x + 4x + 3 = 9x + 3