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$$ \left\{ \begin{matrix} a_0 + a_1 x_1 + a_2 x_1^2 & = & y_1\\ a_0 + a_1 x_2 + a_2 x_2^2 & = & y_1\\ \vdots & = & \vdots \\ a_0 + a_1 x_{21} + a_2 x_{21}^2 & = & y_{21}\\ \end{matrix} \right. $$¥ç¥i¼g¦¨
$$ \underbrace{ \left[ \begin{matrix} 1 & x_1 & x_1^2\\ 1 & x_2 & x_2^2\\ \vdots & \vdots & \vdots\\ 1 & x_{21} & x_{21}^2\\ \end{matrix} \right] }_A \underbrace{ \left[ \begin{matrix} a_1\\ a_2\\ a_3\\ \end{matrix} \right] }_\theta = \underbrace{ \left[ \begin{matrix} y_1\\ y_2\\ \vdots\\ y_{21}\\ \end{matrix} \right] }_y $$¨ä¤¤ $A$¡B$y$ ¬°¤wª¾¡A$\theta$ ¬°¥¼ª¾¦V¶q¡C«Ü©úÅ㪺¡A¤Wz¤èµ{²Õ§t 21 Ó¤èµ{¦¡¡A¦ý«o¥u¦³ 3 Ó¥¼ª¾¼Æ $\theta=\left[\theta_1, \theta_2, \theta_3 \right]^T$¡A©Ò¥H³q±`¤£¦s¦b¤@²Õ¸Ñ¨Óº¡¨¬³o 21 Ó¤èµ{¦¡¡C¦b¤@¯ë±¡ªp¤U¡A§ÚÌ¥u¯à§ä¨ì¤@²Õ $\theta$¡A¨Ï±oµ¥¸¹¨âÃ䪺®t²§¬°³Ì¤p¡A¦¹®t²§¥i¼g¦¨
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