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.