对于由n个未知数，n个方程组成的组多元一次方程组：

a11X1+a12X2+．．．+a1nXn = b1

a21X1+a22X2+．．．+a2nXn = b2

．．．．．．

an1X1+an2X2+．．．+annXn = bn

写成矩阵形式为Ax=b，其中A为系数n*n方阵，x为n个变量构成列向量，b为n个常数项构成列向量。当它的系数矩阵可逆，或者说对应的行列式|A|不等于0的时候，由Ax=b可得：x=b*A-1 ，A-1为A的逆矩阵。-For the group consisting of n unknowns, n equations consisting of a multivariate equations:

a11X1+ a12X2+. . .+ a1nXn = b1

a21X1+ a22X2+. . .+ a2nXn = b2

. . . . . .

an1X1+ an2X2+. . .+ annXn = bn

Written in matrix form as Ax = b, where A is the coefficient n* n matrix, x is a column vector of n variables constituting, b is a constant term n column vectors constituting. When it s reversible coefficient matrix, or the corresponding determinant | A | is not equal to 0, by the Ax = b can be obtained: x = b* A-1, A-1 is the inverse matrix A.