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Let `A=[(1,2),(-1,3)]` .If `A^6=kA-205I` then then numerical quantity of `k-40` should be |
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Answer» `A=[(1,2),(-1,3)]` `implies A^(2)=[(1,2),(-1,3)][(1,2),(-1,3)]=[(-1,8),(-4,7)]=4A-5I` `implies A^(3)=A A^(2)=A(4A-5I)` `=4A^(2)-5A` `=4(4A-5I)-5A` `=11 A-20 I` `A^(6)=A^(3) A^(3)=(11A-20I)^(2)` `=121A^(2)-440 A+400 I` `=121 (4A-5I)-440 A+400 I` `=44A-205 I` |
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