3. (10%) Let \( A=[\mathbf{a}_1, \mathbf{a}_2, \mathbf{a}_3] \) be a 3x3 matrix and suppose that \( 2\mathbf{a}_1+\mathbf{a}_2-4\mathbf{a}_3=\mathbf{0} \). How many solutions will the system \( A\mathbf{x}=\mathbf{0} \) have?