I'm studying music theory in https://www.musictheory.net I have reach a point where the roman numeral analysis is explained.
A couple of lessons later, I found the next image:
I really can't make any sense out of it. You can see the first I is F, and the second I is an A! Also, ther V7 indicated, from my undestanding should be a IV.
I though it may have something to do with inversion, but how would you inverse a single note?
I am really confused, I don't know if I just didn't understand anything about roman numeral analysis, or if there is an error in that image.
Could anyone shed any light on this matter?