Answer:
The expression will be 3(2^x) + 5
Step-by-step explanation:
In order to find the new expression, you have to let g(x) be the x :
[tex]f(x) = 3x + 5[/tex]
[tex]g(x) = {2}^{x} [/tex]
[tex]fg(x) = 3( {2}^{x} ) + 5[/tex]