regression trees and recursive partitions

[akerman]

Hello,

I am really struggling with some basic things related to regression tree. Mainly I do not understand how I am suppose to calculate square error and form the recursive partition.

Here is the set-up:

I have a dataset $\{((1,1),9),((1,2),-4),((1,3),2),((2,2),4),((2,3),2)\}$ and I need to find the regression tree corresponding tot the greedy recursive partitioning procedure with respect to square error.

And then I would like to draw the recursive partition.

I literally have no idea how to even start solving this and it does not seem too difficult as well. Could someone help me out and possibly put detailed solution or partial solution. Anything will be helpful.