2x1-x2+3x 例12解方程组:4x1-2x+5x34, 2x1-x2+4x3=0 解:经初等变换,得 2x1-x2+3x3=1,例1.2 解方程组： 2x1−x2+3x3=1, 4x1−2x2+5x3=4, 2x1−x2+4x3=0. 解：经初等变换，得 2x1−x2+3x3=1, −x3 x3 = 2, = −1