Maximize \mathrm{Z}=\mathbf{x}+\mathbf{y} subject to \mathbf{x}+4 \mathbf{y} \leq \mathbf{8}, 2 \mathbf{x}+3 \mathbf{y} \leq \mathbf{1 2}, 3 \mathbf{x}+\mathbf{y} \leq \mathbf{9}, \mathbf{x} \geq \mathbf{0}, \mathbf{y} \geq \mathbf{0}.
Maximize \mathrm{Z}=\mathbf{x}+\mathbf{y} subject to \mathbf{x}+4 \mathbf{y} \leq \mathbf{8}, 2 \mathbf{x}+3 \mathbf{y} \leq \mathbf{1 2}, 3 \mathbf{x}+\mathbf{y} \leq \mathbf{9}, \mathbf{x} \geq \mathbf{0}, \mathbf{y} \geq \mathbf{0}.

Solution:

It is given that: Z=x+y subject to constraints, x+4 y \leq 8

2 x+3 y \leq 12,3 x+y \leq 9, x \geq 0, y \geq 0

Now construct a constrain table for the above, we have

Here, it can be seen that \mathrm{OABC} is the feasible region

Table for x+4 y=8

    \[\begin{tabular}{|l|l|l|} \hline $\mathrm{x}$ & 0 & 8 \\ \hline $\mathrm{y}$ & 2 & 0 \\ \hline \end{tabular}\]

Table for 2 x+3 y=12

    \[\begin{tabular}{|l|l|l|} \hline $\mathrm{x}$ & 0 & 6 \\ \hline $\mathrm{y}$ & 4 & 0 \\ \hline \end{tabular}\]

Table for 3 x+y=9

    \[\begin{tabular}{|l|l|l|} \hline $\mathrm{x}$ & 3 & 0 \\ \hline $\mathrm{y}$ & 0 & 9 \\ \hline \end{tabular}\]

On solving equations x+4 y £ 8 and 3 x+y £ 9, we obtain
x=28 / 11 \text { and } y=15 / 11
Here, it can be seen that \mathrm{OABC} is the feasible region whose corner points are \mathrm{O}(0,0), \mathrm{A}(3,0), \mathrm{B}(28 / 11,15 / 11) and \mathrm{C}(0,2) .

Let’s evaluate the value of Z

    \[\begin{tabular}{|l|l|} \hline Corner points & Value of $Z=x+y$ \\ \hline $0(0,0)$ & $Z=0+0=0$ \\ \hline$A(3,0)$ & $Z=3+0=3$ \\ \hline$B(28 / 11,15 / 11)$ & $Z=28 / 11+15 / 11=43 / 11=3.9$ \\ \hline \end{tabular}\]

\mathrm{C}(0,2)

\mathrm{Z}=0+2=2

It is observed from the above table that the maximum value of \mathrm{Z} is 3.9

Thus, the maximum value of \mathrm{Z} is 3.9 at (28 / 11,15 / 11).