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If `A=[5a-b3 2]`and A adj `A=AA^T`, then `5a+b`is equal to:(1) `-1`(2) 5(3) 4 (4)13A. 5B. 13C. 4D. -1 |
Answer» Correct Answer - A `because A" adj "A = A A^(T)` `rArr A^(-1) (A" adj " A) = A^(-1) (A A^(T))` `rArr (A^(-1)A)" adj " A = (A^(-1) A) A^(T)` `rArr I ( " ADj " A ) = IA^(T)` or ` " adj " A = A^(T)` or `[[2,b],[-3,5a]]=[[5a,3],[-b,2]]` `rArr 5 a = 2 and b = 3` `therefore 5a + b = 5` |
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