The system Ax=b can be solved as x = A\b.  This is equivalent to x = Inv(A)*b when A is square.  It is equivalent to Pinv(A)*b when A is not square. A and b must have the same number of rows.  If b is a matrix, the system is solved for each column separately, resulting in multiple solutions.

Here is an example:

A = [1,2,3;41,15,6;17,8,9];// square matrix

b = [11;22;21];

print(A\b)

The result is:

[Matrix] 3 x 1

      -1.7368

       6.1579

      0.14035

 

If b is a two column matrix, for example, then the output would be the solutions to two systems, one for each column of b:

b = [11,21;13,33;21,24];

print(A\b)

The result is:

[Matrix] 3 x 2

         -1.5         -5.4079

          4.5          18.355

       1.1667         -3.4342