%PARTE 1

 %3a.
 A=[1 1 1 1; 1 1 4 2; 2 9 9 3];
 X=rref(A)

 %3b.
 clear
 A=input('[1 1 1 1; 1 1 4 2; 2 9 9 3]');
X=rref(A)
[L,C]=size(X);
n=L;
m=C;
if X(n,m-1)==0 & X(n,m)==0
 disp('o sistema e indeterminado')
else if X(n,m-1)==0 & X(n,m)~=0
 disp('o sistema e impossivel')
 else
 disp(' a solucao e:')
 for j=1:n
 X(j,m)
 end
 end
end

%PARTE 2
clear
A=[2 7 3 2 1 9; 1 3 2 4 -1 -4; 2 7 6 6 2 -4; 8 9 0 4 -3 17; -1 2 1 1 1 -1];
X=rref(A)
clear


%PARTE 3
clear