[tex] \large \boxed{(f + g)(x) = f(x) + g(x)}[/tex]
Use the following property above to find the value. Substitute f(x) and g(x) in.
[tex] \large{(2x + 3) + ( {x}^{2} - 8)} \\ \large{2x + 3 + {x}^{2} - 8}[/tex]
Evaluate/Combine like terms.
[tex] \large{2x + {x}^{2} - 5}[/tex]
This step is optional but it's the best to arrange the degree.
[tex] \large{ {x}^{2} + 2x - 5} \\ \large{(f + g)(x) = {x}^{2} + 2x - 5}[/tex]
Answer
Let me know if you have any doubts!