If the rank of a square matrix of order 4 is 2, what is the rank of its adjoint matrix?

If the rank of a square matrix of order 4 is 2, what is the rank of its adjoint matrix?


The rank is 0
Because the rank of matrix A of order 4 is 2, its third-order formulas must all be 0 (otherwise the rank will be 3)
Since all the third-order subformulas are 0, then according to the definition of adjoint matrix, its elements are all 0, that is, it is a 0 matrix, so its rank is 0