回覆 9# mojary 的帖子
填充11.
注意到 \( (217,175) + (188,410) = (405,585) = 3 (135,195) \)
故 \( P(135 , 195) \) 經過矩陣 \( A \) 變換為 \( \frac13 (83+112,125-110) = (65,5) = 5(13,1) \)
故所求 = \( 5 \cdot \left[\begin{array}{cc} \frac{ - 3}{5} & \frac{4}{5} \\ \frac{4}{5} & \frac{3}{5} \end{array}\right]\left[\begin{array}{cc} 13 \\ 1 \end{array}\right] = \left[\begin{array}{cc} - 35 \\ 55 \end{array}\right] \)，所求即 \( (-35,55) \)
