x=4,x+y=z
5x+3y-3z
=20+3y-3(4+y)
=8
(5X+3Y-3Z)^2008
=8^2008
找规律:
8^1末尾8,
8^2末尾4,
8^3末尾2,
8^4末尾6.
8^5末尾又变为8了.
故是4位一循环,
2008=4*502
故8^2008末尾与8^4相同,也为6.