To solve $(f + g)(3)$, you need to know the functions $f(x)$ and $g(x)$.

The process would be as follows:

1. Define $f(x)$ and $g(x)$.
2. Add the two functions: $(f + g)(x) = f(x) + g(x)$.
3. Substitute $x = 3$ into the equation.
4. Simplify the expression to get the final answer.

If you provide the expressions for $f(x)$ and $g(x)$, I can proceed with the solution.

Would you like to clarify the functions, or have any questions?

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Here are 5 follow-up questions that might help you understand this better:

1. What are the exact forms of $f(x)$ and $g(x)$?
2. What happens when you combine two functions algebraically?
3. How do you simplify expressions involving radicals?
4. Can this approach be used with any real numbers for $x$?
5. What does function composition mean in comparison to function addition?

Tip: When dealing with radicals, simplify them as much as possible before combining terms.