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 ta