Well, I didn't knew the rules before posting the 3 excercises, shame on me.
But now I Do.
I added my attemp to solve excercise number 1 (look my comment on it); and excercise number 2 I solved it outside this forum (it can be erased). So the only left is excercise number 3, and i will add my attemp soon.
Please don't overreact; i'm just a guy that needs help; it was't my aim to bother the forum.