why the sum of residuals must always equal zero?


I was wondering why the sum of the residuals of a simple regression line must always equal zero. It simply blows my mind that it could always be true. Please help me wrap my mind around this concept.



Ambassador to the humans
Uh... That's pretty much one of the only terms that doesn't evaluate to 0. \(\sum(x_i - \bar{x})\) is 0 though so when you multiply r(sy/sx) by 0 you get 0.