说明：  高斯消去法求解AX=b，利用对增广矩阵进行的初等行变换，将系数矩阵变为上三角矩阵，然后回带，可以得到方程组的解。
(Gaussian elimination method for solving AX = b, using the augmented matrix for the elementary row transformation, the coefficient matrix into an upper triangular matrix, and then back to the tape, you can get the solution of the equations.)