This is very similar to evaluating functions. There's one thing to keep in mind, though. If you see f(x + 2), that means to plug (x + 2) into the function. (I recommend putting it in parentheses, so you'll remember that it's one unit.) If you see f(x) + f(2), on the other hand, that means to plug x into the function, and to plug 2 in separately, and to add the results.