Linear algebra A ^ 2 = I, then a = I or - I is right

Linear algebra A ^ 2 = I, then a = I or - I is right

incorrect
A^2=AA=I
A^(-1)AA=A^(-1) I
IA=A=A^(-1)I=A^(-1)
When a = a ^ (- 1)
AA=A^2=I

In linear algebra, what is the concept of multiplicity of eigenvalue λ (I)?

For example, | a - λ e | = (1 - λ) ^ 2 (2 + λ) ^ 3
If the eigenvalues are 1, - 2, then the multiplicity of eigenvalue 1 is 2 and the multiplicity of eigenvalue - 2 is 3

What does linear algebra e (I (k)) e (I + (k), I) mean
It's better to give an example. Just say the meaning. Thank you

Let's talk about elementary matrixes. Specifically, there are three kinds of elementary matrixes, which correspond to three kinds of elementary transformations (1) e respectively. The matrix obtained by the row (column) interchange of I and j is e (I & nbsp;, & nbsp; J & nbsp;) such as e (2,3) (2) e multiplied by the non-zero number K

What does linear algebra R (a) mean

The rank of matrix A