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If `A` is an invertible matrix, then `(a d jdotA)^(-1)` is equal to a.`a d jdot(A^(-1))` b. `A/(d e tdotA)` c. `A` d. `(detA)A`

A

adj. `(A^(-1))`

B

`A/("det. A")`

C

`A`

D

(det. A) A

Text Solution

Verified by Experts

`A^(-1)=("adj (A)")/(|A|)`
`:. ("adj A")^(-1)=("adj (adj A)")/(|"adj A"|)`
`=(|A|^(n-2) A)/(|A|^(n-1))`
`=A/(|A|)`
Also A (adj A) `=|A|I`
or `A^(-1) ("adj "A^(-1))=|A^(-1|I`
or `A^(-1) ("adj "A^(-1))=I/(|A|)`
or `A A^(-1) ("adj "A^(-1))=(A.I)/(|A|)`
or `I ("adj "A^(-1))=A/(|A|)`
or `("adj "A^(-1))=A/(|A|)=("adj "A)^(-1)`
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