remains positive for all t > 0 .
Lemma 2. All solutions of system (2) will lie in the region
\begin{equation} B=\{(x_{1},x_{2},y)\in\mathbb{R}_{+}^{3}\ :0\leq\ c_{1}x_{1}+{c_{2}x}_{2}+y\leq\frac{M}{\lambda}\}\nonumber \\ \end{equation}
as \(t\rightarrow\infty\)for all positive initial values \(\ (x_{10},x_{20}\), \(y_{0})\ \epsilon\ \mathbb{R}_{+}^{3},\)where \(\lambda<\min{\{r_{1},r_{2},d\}}\) and\(M=r_{1}^{2}+r_{2}^{2}\)