Please answer this question in detail. Thanks a lot!

2. Suppose (Mt, Ft), t=0,l,2,. . .,T is a martingale in discrete time. Meaning that E(Mt+1|Ft)=Mt, for t=0,1,2,. . .,T. Show that this implies the more general relation: E(Mt+1|Fu)=Mu, 11:0, 1,2, . . . ,t [Hint: The appended notes on conditional expectations may be useil in this and similar questions]