2. Which of the following statements are true? If u is a solution to A Ax= Ab, then for any vector v, ||Au-b||||Av-b||. If u is a solution to AAx = A b, then Au is unique. If A Ax= Ab is consistent, it has a unique solution. AT Ax=Ab is always consistent. If u is a solution to A Ax= A b, then Au bis orthogonal to the column space of A.