Answer:
[tex](f+g)(x)=-3x^{2} +5x+3[/tex]
Step-by-step explanation:
The given functions are
[tex]f(x)=-3x^{2} +3[/tex] and [tex]g(x)=5x[/tex]
To find [tex](f+g)(x)[/tex] we just need to sum those functions.
[tex](f+g)(x)=-3x^{2} +3+5x[/tex]
Therefore, the simplest polynomial is [tex](f+g)(x)=-3x^{2} +5x+3[/tex]