Trong mặt phẳng tọa độ Oxy, cho

B

- Hướng dẫn giải

\(A' = {V_{\left( {I;2} \right)}}\left( A \right) \Leftrightarrow \overrightarrow {IA'} = k\overrightarrow {IA} \)

\(\begin{array}{l} \Leftrightarrow \left\{ \begin{array}{l}{x_{A'}} - 3 = 2\left( {1 - 3} \right)\\{y_{A'}} - \left( { - 1} \right) = 2\left( {2 - \left( { - 1} \right)} \right)\end{array} \right.\\ \Leftrightarrow \left\{ \begin{array}{l}{x_{A'}} - 3 = - 4\\{y_{A'}} + 1 = 6\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}{x_{A'}} = - 1\\{y_{A'}} = 5\end{array} \right.\\ \Rightarrow A'\left( { - 1;5} \right)\end{array}\)