So you're given the function f(x)=

. From here it's a simple plug in, since they're giving us our x-value, 2. (If this helps at all) a function is like a machine, you input something and it gives you an output. This these functions (f(x)) our input is an x-value, and we get a y-value. If you think of this and test a bunch of points on a graph then it'll make a whole lot of sense.
So with this problem, your input is 2, and our function (machine that'll give us our output) is

. All you do is plug in 2 for all x's and solve:

= 14
So 14 is your output, and your answer!
(lol sorry you got a whole lesson instead of just the answer :P)