If f(x) = 4x + 10, which expression represents f(x2 + 2)?

In order to determine the answer to this item, we just have to substitute x² + 2 to all x's of the first function. That is,
                  f(x) = 4x + 10
will become,
                 f(x²+2) = 4(x²+2) + 10
Simplifying will give us an answer of,
                f(x²+2) = 4x²+18

The answer would be the second choice : )