For this case we have the following functions:
[tex]f (x) = x ^ 2 + 2x-5\\g (x) = 2x + 4[/tex]
We must find [tex](f * g) (x)[/tex]. By definition we have to:
[tex](f * g) (x) = f (x) * g (x)[/tex]
So:
[tex](f * g) (x) = (x ^ 2 + 2x-5) (2x + 4)[/tex]
Applying distributive property we have:
[tex](f * g) (x) = 2x ^ 3 + 4x ^ 2 + 4x ^ 2 + 8x-10x-20[/tex]
We add similar terms:
[tex](f * g) (x) = 2x ^ 3 + 8x ^ 2-2x-20[/tex]
Answer:
[tex](f * g) (x) = 2x ^ 3 + 8x ^ 2-2x-20[/tex]
