f(x) functions are representative of domains and ranges. The domain would be any legal (the question would tell you what would be a legal x value, like for example f(x) for a domain containing x>0. That means any number greater than or equal to 1) x value inside f(x) and the range would be whatever f(x) equals (your y values).
For what you have given above it seems that the domain and range are 1-to-1 mappings. Whatever x equals for f(x), y also equals. So when x= -2, f(-2) = -2.
I know it seems too easy. If the function was f(x) = 3x-2 then when x=-2..... f(-2) = 3(-2) - 2 = -8. In this instance whenever x =-2, y = -8. This is also an ordered pair if you had to plot the point. (-2,-8).
But yes for your question f(-2) = -2.
Did this help? If so could you please best my answer (choose my answer as the best answer)? Thanks Alyssa!