简答题:
(I)求a的值；
(Ⅱ)求可逆矩阵P．

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966195829571.png" width="98" height="35" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/16196619622481.png" width="120" height="35" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966196694791.png" width="83" height="37" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966197182881.png" width="118" height="37" /> 

A 1 B 2 C 3 D 4

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966198511401.png" width="19" height="37" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966199292021.png" width="19" height="37" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966199616981.png" width="18" height="29" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966200173241.png" width="18" height="29" /> 

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966200594911.png" width="55" height="34" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966200930781.png" width="40" height="35" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966201375481.png" width="84" height="34" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/16196620309201.png" width="70" height="34" /> 

A 4 B 3 C 2 D 1

A <img src="https://www.beizhujiaoyu.com/uploads/202208/161966204567291.png" width="88" height="38" />  B <img src="https://www.beizhujiaoyu.com/uploads/202208/161966204914271.png" width="90" height="38" />  C <img src="https://www.beizhujiaoyu.com/uploads/202208/161966205384621.png" width="95" height="38" />  D <img src="https://www.beizhujiaoyu.com/uploads/202208/161966205868011.png" width="94" height="38" /> 

A x=k₁α₁+k₂α₂+k₃α₃，其中k₁，k₂，k₃为任意常数 B x=k₁α₁+k₂α₂+k₃α₄，其中k₁，k₂，k₃为任意常数 C x=k₁α₁+k₂α₃+k₃α₄，其中k₁，k₂，k₃为任意常数 D x=k₁α₂+k₂α₃+k₃α₄，其中k₁，k₂，k₃为任意常数

A (α₁+α₃，α₂，-α₃) B (α₁+α₂，α₂，-α₃) C (α₁+α₃，-α₃，α₂) D (α₁+α₂，-α₃，α₂)