function y = Ecuacion_Primer_Orden(C, x, yini)
    N = length(x);
    h = x(2)-x(1);

    A = zeros(N-1, N-1);
    b = zeros(N-1, 1);
    for k=1:N-1
        A(k,k) = C(1) + C(2)*h;
        b(k) = C(3)*h;
        if k>1
            A(k, k-1) = -C(1);
        else
            b(k) = b(k)+ C(1)*yini;
        end;
    end;
    A
    b
    y = [yini; A\b];
end