Question

If A and B non-singular matrix then, which of the following is incorrect? 

(a) A² = I implies A^-1 = A 

(b) I^-1 = I 

(c) If AX = B then X = B^-1 A 

(d) If A is square matrix of order 3 then |adj A| = |A|²

Answer 1

(c) If AX = B then X = B^-1 A

If AX = B then X = A^-1 B so, X = B^-1 A is incorrect.