3x-y+z=4-----1式2x+3y-z=12-----2式x+y+z=6-----3式1式 + 3式,得：4x + 2z = 10 ---->2x + z = 5------4式3式 * 3 - 2式,得：x + 4z = 6 -------5式5式 * 2 - 4式,得：7z = 7 -----> z = 1将z = 1代入3式：x + y = 5 ------6式将z = 1代入1式：3x - y = 3 ------7式6式 + 7式,得：4x = 8 ------>x = 2将x = 2代入6式：2 + y = 5----->y = 3所以：x = 2;y = 3;z = 1;