And 8x belongs in 28x's class, since 8x and 28x share a tail.
I think the author meant for you to interpret "equal after a finite number of entries" in the more normal fashion (e.g., 123x = 456x but 1x != 111x, the prefixes have to have equal length.) But your way seems to work fine too.
I think the author meant for you to interpret "equal after a finite number of entries" in the more normal fashion (e.g., 123x = 456x but 1x != 111x, the prefixes have to have equal length.) But your way seems to work fine too.