1.

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`


Discussion

No Comment Found

Related InterviewSolutions