I hope I'm at right place, as I asked this question at stackoverflow.com where the question was closed and suggested I go ask here. I'll try to be more comprehensive also, looking at couple of replies I got there.
The question is simple for those who know how algorithms work, and as I'm physics student I'm not sure about the answer. I had exam in Statistics where professor suggested that formula I used (red outlined) in determining "Least-Squares Regression Line" was computationally inferior to the one derived below (green outline). My simple thinking was that first one uses n squares while derived (n+1) squares, but supposedly that's not enough. Can someone point why could derived formula be computationally more effective?