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Property

Involutory matrices

A2=I    A1=AA^2 = I \iff A^{-1} = A
II
the identity matrix

A matrix whose square is the identity is its own inverse, and its even powers are the identity.

16
questions use it
7
of them past-year
2017–2026
years it has appeared
6%
rated HARD
3
exams
Matrices & Determinants notesOpen all 16 in the paper builder

Used alongside

How often each of these appears in the same solution as this one.

16 questions whose solution uses this

Every one was read individually — a question is here because its solution invokes this, not because the stem mentions it.

Every identity this chapter tests, with its own question set.

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