题目内容
4.已知矩阵M=$(\begin{array}{l}{0}&{1}\\{1}&{0}\end{array})$,N=$(\begin{array}{l}{0}&{-1}\\{1}&{0}\end{array})$(Ⅰ)求矩阵MN;
(Ⅱ)若点P(0,1)在矩阵MN对应的线性变换作用下得到点P′,求P′的坐标?
分析 (Ⅰ)利用矩阵的乘法,求矩阵MN;
(Ⅱ)利用矩阵MN对应的线性变换,结合矩阵的乘法,求P′的坐标.
解答 解:(Ⅰ)∵M=$(\begin{array}{l}{0}&{1}\\{1}&{0}\end{array})$,N=$(\begin{array}{l}{0}&{-1}\\{1}&{0}\end{array})$
∴矩阵MN=$(\begin{array}{l}{0}&{1}\\{1}&{0}\end{array})$$(\begin{array}{l}{0}&{-1}\\{1}&{0}\end{array})$=$[\begin{array}{l}{1}&{0}\\{0}&{-1}\end{array}]$;
(Ⅱ)设P′(x,y),则$[\begin{array}{l}{x}\\{y}\end{array}]$=$[\begin{array}{l}{1}&{0}\\{0}&{-1}\end{array}]$$[\begin{array}{l}{0}\\{1}\end{array}]$=$[\begin{array}{l}{0}\\{-1}\end{array}]$,
∴P′(0,-1).
点评 本小题主要考查矩阵与变换等基础知识,考查化归与转化思想,属于基础题.
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