laz0r
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Homework Statement
Prove that
\sum[(x_{i} - \overline{x})(y_{i} - \overline{y})] = \sum[(x_{i} - \overline{x})y_{i}]
Homework Equations
None.
The Attempt at a Solution
I tried using the fact that the sum of the mean values is just the mean value, because the sum of a constant is simply a constant, and I expanded out the first sum, but I didn't end up anywhere.
\sum[x_{i}y_{i}] - \overline{y}\sum(x_{i}) - \overline{x}\sum(y_{i}) + \overline(x)\overline(y)
I have no idea where to go from here, so some inspiration would be much appreciated.