Solve Ax=b (and check the solution) given that

       1  2  0       7
   A = 2  5 -1   b = 8
       4 10 -1       9
 

 A=[[1;2;4];[2;5;10];[0;-1;-1]]
 b=[7;8;9]
 soln = gaussj(A,b)
 check = b-A<>soln

The check vector should be all zero if the solution is correct.

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