For this case we have the following functions:
[tex]f (x) = 3x\\g (x) = x + 7[/tex]
We must find [tex](f_ {0} g) (x)[/tex]. By definition we have to:
[tex](f_ {0} g) (x) = f (g (x))[/tex]
So:
[tex]f (g (x)) = 3 (x + 7) = 3x + 3 * 7 = 3x + 21[/tex]
Finally, the composite function is:
[tex](f_ {0} g) (x) = 3x + 21[/tex]
Answer:
[tex](f_ {0} g) (x) = 3x + 21[/tex]
