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If A and B are n-rowed unitary matrices,then AB and BA are also unitary matrices. |
Answer» A and B are two orthogonal matrices. Hence, `A^(T)A=A A^(T)=I` and `B B^(T)=B^(T)B=I` AB will be orthogonal if `(AB)^(T) (AB)=(B^(T)A^(T)) (AB)` `=B^(T) (A^(T)A)B` `=B^(T) IB` `=B^(T)B=I` Similarly, we can show that `(BA)^(T) (BA)=I`. Therefore, Ba is also orthogonal. |
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