- #1
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Why does it follow from
[tex]
\frac{d}{d\beta}(-\Sigma_{i=1}^n[\frac{(y_i - \alpha - \beta x_i)^2}{2 \sigma^2}]) = 0
[/tex]
that
[tex]
\Sigma_{i=1}^n x_i(y_i - \alpha - \beta x_1) = 0
[/tex]
?
[tex]
\frac{d}{d\beta}(-\Sigma_{i=1}^n[\frac{(y_i - \alpha - \beta x_i)^2}{2 \sigma^2}]) = 0
[/tex]
that
[tex]
\Sigma_{i=1}^n x_i(y_i - \alpha - \beta x_1) = 0
[/tex]
?