clc, clear all, close all
%Matriz Gauss Simple
A=[15,-24,3,30;5,-6,8,7;1,2,3,5;-25,40,-5,-50];
b=[-33;0;-6;55];

%Matriz Ampliada
a=[A,b]
det(A)

%S.C.D.
%Cero en a(2,1)
a(2,:)=a(1,1)*a(2,:)-a(2,1)*a(1,:)

%Cero en a(3,1)
a(3,:)=a(1,1)*a(3,:)-a(3,1)*a(1,:)

%Cero en a(4,1)
a(4,:)=a(1,1)*a(4,:)-a(4,1)*a(1,:)

%Cero en a(3,2)
a(3,:)=a(2,2)*a(3,:)-a(3,2)*a(2,:)

%Cero en a(4,2)
a(4,:)=a(2,2)*a(4,:)-a(4,2)*a(2,:)

%Cero en a(4,3)
a(4,:)=a(3,3)*a(4,:)-a(4,3)*a(3,:)

%Sustitución hacia atrás
d=a(4,5)/a(4,4)
c=(a(3,5)-a(3,4)*d)/a(3,3)
b1=(a(2,5)-a(2,4)*d-a(2,3)*c)/a(2,2)
a1=(a(1,5)-a(1,4)*d-a(1,3)*c-a(1,2)*b1)/a(1,1)

%Comprobando
a1b1cd=[a1;b1;c;d]
A*a1b1cd
b