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Let `A` and `B` be two non-singular square matrices such that `B ne I` and `AB^(2)=BA`. If `A^(3)-B^(-1)A^(3)B^(n)`, then value of `n` isA. `4`B. `5`C. `8`D. `7` |
Answer» Correct Answer - C `(c )` `BA=AB^(2)` `impliesBA=AB^(2)` `impliesA=B^(-1)AB^(2)` `impliesA^(2)=(B^(-1)AB^(2))(B^(-1)AB^(2))` `=B^(-1)A(BA)B^(2)` `impliesB^(-1)A AB^(2)B^(2)` `=B^(-1)A^(2)B^(4)` `:.A^(3)=B^(-1)A^(3)B^(6)` |
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