. Is it possible to have AB=In without B being the inverse of A?

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SUMMARY

The discussion centers on the mathematical question of whether the product of two matrices, AB, can equal the identity matrix In without B being the inverse of A. The matrices provided are A = |1 1 0|, |0 1 0| and B = |1 -1|, |0 1|, |0 0|. The conclusion drawn is that this is possible when A and B have different dimensions, as demonstrated by the example where AB results in the identity matrix I(2), while BA does not equal the identity matrix I(3).

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Homework Statement



30.
Is it possible to have AB= In without B being the inverse of A? Explain your reasoning.

Homework Equations


The Attempt at a Solution


yes if A=
|1 1 0|
|0 1 0|
B=

|1 -1|
|0 1|
|0 0|
AB=I(2) , BA=! I3 right?
 
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That would be true once A and B do not have the same dimensions (as you showed using an example)
 

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