To get straight to the point: I have to prove, using a truth-tree, that the following set of propositions (image 2) is contradictory. You can see the way I proceeded in image 3 and the way the exemple is solved in the book in image 1.
At one point I have started "decomposing" proposition no.3 and the book proposition no.2 - which lead us to a different order of tree-branches and a different ending (mine does not end in a contradiction, if I the problem correctly).
I guess somewhere I went wrong, or I didn't follow through or I just simply don't get something - if anyone can help it would I would be really thankful!
[![enter image description here]](https://i.stack.imgur.com/JXX5v.jpg)
[![enter image description here]](https://i.stack.imgur.com/mvrn9.jpg)