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How many different diagonal matrices of order n can be formed which are idempotent ? |
Answer» Correct Answer - `2^(n)` Matrix A is diagonal matrix. `:. A`=dia. `(a_(1), a_(2), ..., a_(n))` `implies A^(2)=` dia. `((a_(1))^(2), (a_(2))^(2),..,(a_(n))^(2))` since A involuntary, we have `:. A^(2)=A` `implies (a_(1))^(2)=a_(1), (a_(2))^(2)=a_(2), ..., (a_(n))^(2)=a_(2),...,(a_(n))^(2)=a_(n)`. `implies a_(1), a_(2), ..., a_(n)=0, 1`. Thus, number of required matrix A is `2xx2xx2xx...n` times `=2^(n)` |
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