Exam 2, Question 63

[Nitin Iyer]

Exam 2, Question 63

[Anonymous]

Question 63 : Which of the following statements are true:
I. Matrices can be added or subtracted only if they are of the same order
II. Matrices of the same order cannot be multiplied unless they are square matrices
III. One square matrix can be divided only by another square matrix
IV. If A is a square matrix and A- its inverse, the AA- = A-A

Answer: Statement IV is correct, it correctly describes the behavior of an inverse.

Would it be possible to explain how IV is true.

A*A- is the identity matrix, but A minus A is zero, and not the identity matrix. I am confused.

[Anonymous]

It is just a case of typo. It is not A-A, but it is A times A to the power of -1
So it is A^-1*A=A*A^-1

[Author]

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