If $A=\begin{bmatrix} 0 & -1 \\ 1 & 0 \end{bmatrix}$ then which one of the following statements is not correct ?

Question

$\begin{array}{1 1} A^4-I=A^2+1 \\ A^3-I=A(A-1) \\ A^2+1=A(A^2-I) \\ A^3+I =A(A^3-1) \end{array}$