∵A−1=∣A∣1(adj(A))
∴adj(adjA)=∣adjA∣(adjA)−1=∣A∣2(adjA)−1……(i)
∵A(adjA)=∣A∣I
∴adj(A)=∣A∣A−1
∴(adjA)−1=∣A∣1A
∴from(i)adj(adjA)=∣A∣.A
JEE Main 2017 — Mathematics Algebra
Let A be any 3×3 invertible matrix. Then which one of the following is not always true?
Held on 8 Apr 2017 · Verified 6 Jul 2026.
adj(adj(A))=∣A∣2.(adj(A))−1
adj(adj(A))=∣A∣.(adj(A))−1
adj(adj(A))=∣A∣.A
adj(A)=∣A∣.A−1
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