Let a be a square matrix of order n, and the square of a = e (or identity matrix), then why should all eigenvalues of a be justified

Let a be a square matrix of order n, and the square of a = e (or identity matrix), then why should all eigenvalues of a be justified

Let a be the eigenvalue of A
Then a ^ 2-1 is the eigenvalue of a ^ 2-e (theorem)
The eigenvalue of a ^ 2-e = 0,0 matrix can only be 0
So a ^ 2-1 = 0
So a = 1 or - 1
The eigenvalue of a is 1 or - 1

Elden Ring Premiere

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