Respuesta :

If [tex]A^3=I[/tex], then [tex]A^3=AA^2=I[/tex] which means [tex]A[/tex] and [tex]A^2[/tex] must be inverses of one another, so [tex](A^2)^{-1}=A[/tex] and [tex]A^{-1}=A^2[/tex], so [tex]A[/tex] must be invertible.