Given:
[tex]\begin{gathered} F(x)=x^2+1 \\ g(x)=5-x \end{gathered}[/tex]The objective is to find (F+g)x.
[tex]\begin{gathered} (F+g)x=F(x)+g(x) \\ (F+g)x=x^2+1+5-x \\ (F+g)x=x^2-x+6 \end{gathered}[/tex]Hence, the equation of (F+g)x is,
[tex]x^2-x+6[/tex]