The third temptation gives the game away. Jesus finds out what Satan really wants. Satan already knows that Jesus has come to redeem the world. If you want it that much, I'll give it to you. All you have to do is bow down to me.
This is a simple trick. Anyone should be able to spot the logical problem here – it doesn't take Jesus a second. Worship me and not God, and have what you came for the easy way, but of course you don't really have it, if you've changed masters – Satan would still have it.
If Jesus falls for this he really has thrown it all away, after all, he would have to give up his relationship with his father, and of course he is not prepared to do that. There would of course be no need for the cross, no need to die in shame, a painful and horrible death.
Jesus has had enough “Away from me” - A command direct to the devil, that has the authority of God, and so must be obeyed.