For this case we have the following functions:
[tex]f (x) = 3x\\g (x) = x ^ 2 + 1[/tex]
We must find (f + g) (x). By definition of operations with functions we have to:
(f + g) (x) = f (x) + g (x)
So we have to:
[tex](f + g) (x) = 3x + (x ^ 2 + 1)\\(f + g) (x) = x ^ 2 + 3x + 1[/tex]
Answer:
[tex](f + g) (x) = x ^ 2 + 3x + 1[/tex]
Option B