Solution
= Solution
For $Y\sim N_n(X\beta,\sigma^2I)$,
$$
\ell(\beta,\sigma^2)
=-\frac n2\log(2\pi)-\frac n2\log\sigma^2
-\frac1{2\sigma^2}\|Y-X\beta\|_2^2.
$$
= Solution
For $Y\sim N_n(X\beta,\sigma^2I)$,
$$
\ell(\beta,\sigma^2)
=-\frac n2\log(2\pi)-\frac n2\log\sigma^2
-\frac1{2\sigma^2}\|Y-X\beta\|_2^2.
$$