6. Let aij, bk R, i, j, k = {1, 2, 3} be given, and consider the following system of linear equations for the unknowns x1, x2, x3 ER: a111a12x2 + a13x3 = b a21x1a22x2 + a23x3 = a31x1a32x2 + A33x3 = b3 Assume that this system has a unique solution. Under this assumption, does the system composed of the first and the second equations have a unique solution, no solution, or infinitely many solutions? You have to fully justify your answer. [6]