Counterexample

Is this true?

AB = I ⇒ BA = I for all matrices

No — it is false.

The counterexample

The object that kills this claim comes with Trap Analysis.

86 counterexamples are free — including most of the ones Part C leans on hardest.

Keep practicing

Execution slip

The idea was right. The computation was not.

See real exam options built on this mistake Drill statements like this

Go deeper· Explained in full in Determinants, trace and block matrices· Asked in CSIR NET December 2024· From Determinants and Matrix Tricks › Determinants, trace, block matrices, rank inequalities

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