| （选修4-2：矩阵与变换） 已知矩阵A=
|
由矩阵A属于特征值6的一个特征向量为α1=
可得1 1 3 3 c d
=61 1
，1 1
即c+d=6； …（3分）
由矩阵A属于特征值1的一个特征向量为α2=
，可得3 -2 3 3 c d
=3 -2
，3 -2
即3c-2d=-2，…（6分）
解得即A=
，…（8分）3 3 2 4
∴A逆矩阵是A-1=
=d ad-bc -b ad-bc -c ad-bc a ad-bc
．2 3 - 1 2 - 1 3 1 2
| 阅读理解，根据短文材料完成表格。 | ||||||||||||
| I've celebrated Christmas many times, but this is the first time with family and relatives. My cousins from my mum's side invited us for Christmas celebration at their house this year. I don't see them often, as generally we're not that close to them. A bit history of them here. They were the children of my second uncle. He had two wives. The cousins I met there were from both. Four daughters and a son from the first, and two sons from the second. The rest were not around. The house we went to is in Tropicana, which was extremely large. I enjoyed the celebration we had yesterday. It's the usual stuff I've seen on TV, and heard from friends who celebrate them. Caroling (圣颂歌), having dinner, social talks, introduction of who is whose children etc., and not to miss, the food, delicious. I like the turkey sandwich. As usual, I looked and walked around after dinner, and to my surprise, two of my nephews, aged 22 and 25, look really beautiful, just like movie stars. The nieces were not bad at all. Some are very pretty, and the rest are all above average. We left about 11:30 pm. I sure hope to meet them again in the near future. Hopeful]y when rny cousin that I meet quite regularly, had her open house, also in Tropicana. | ||||||||||||
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