# Math Help - Linear System

1. ## Linear System

Suppose $A$ is a square matrix and the homogeneous system $(A^2)^T X = 0$ has a unique solution.Can any conclusion be made on the linear system $AX=0$.

2. Yes, $AX=0$ has unique solution

Proof :
$rank(A)=rank(A^T)$ ref attachment
$n\geq rank(A)\geq rank(A^2)=rank((A^2)^T)=n\rightarrow rank(A)=n$
So $AX=0\rightarrow X=A^{-1}0=0$