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If B is an idempotent matrix, and `A=I-B`, thenA. `A^(2)=A`B. `A^(2)=I`C. `AB=O`D. `BA=O` |
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Answer» Correct Answer - A::C::D B is an idempotent matrix `:. B^(2)=B` Now, `A^(2)=(I-B)^(2)` `=(I-B) (I-B)` `=I-IB-IB+B^(2)` `=I-B-B+B^(2)` `=I-2B+B^(2)` `=I-2B+B` `=I-B` `=A` Therefore, A is idempotent. Again, `AB=(I-B)B=IB-B^(2)=B-B^(2)=B^(2)=B^(2)-B^(2)=O` Similarly, `BA=B(I-B)=BI-B^(2)=B-B=O`. |
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