If AB=I, then A is invertible. False

Dustinsfl · Apr 30, 2010

If AB=I, then A is invertible.

False, but not sure how to show it.

Mark44 · Apr 30, 2010

Dustinsfl said:

If AB=I, then A is invertible.

False, but not sure how to show it.

There's no requirement that A and B have to be square matrices. I came up with a 2x3 matrix and a 3x2 matrix whose product is I, a 2x2 matrix, yet neither of the matrices in the product is invertible.

Dustinsfl · Apr 30, 2010

Thanks, I figured out a matrix that works.

malmir · Nov 13, 2011

If A(n*n) and B (n*n).
and If AB=I.
is A invertible?
is B inverse of A?

If AB=I, then A is invertible. False

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If AB=I, then A is invertible. False

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