A = [ 9 -4 -2 0; -4 17 -6 -3 ; -2 -6 14 -6 ; 0 -3 -6 11]

b = [48 ; -32 ; 0 ; 36 ]

% Löse A * I = b;
I = zeros(4,1);

I = A \ b;

[LA, UA, PA] = lu(A)

LA*UA \ PA*b