Consider the following IP problem:

Minimize [tex]z = 4x_1 + x_2[/tex]

subject to

[tex]
\begin{aligned}
3x_1 + x_2 & = 30 \\
4x_1 + 3x_2 & \ \textgreater \ 60 \\
x_1 + 2x_2 & \leq 40 \\
x_1, x_2 & \geq 0
\end{aligned}
[/tex]

The starting solution consists of artificial variables [tex]x_4[/tex] and [tex]x_5[/tex] for the first and second constraints and slack variable [tex]x_6[/tex] for the third constraint. Using [tex]M=100[/tex] for the artificial variables, find the optimal solution.



Answer :

To solve the linear programming problem, we need to use the standard methods for optimization while taking into account the provided constraints. The goal is to minimize the objective function [tex]\( z = 4x_1 + x_2 \)[/tex].

Let's start by rewriting the problem:

### Objective
[tex]\[ \text{Minimize } z = 4x_1 + x_2 \][/tex]

### Subject to
[tex]\[ \begin{aligned} 3x_1 + x_2 &= 30 \quad \text{(Constraint 1)} \\ 4x_1 + 3x_2 &> 60 \quad \text{(Constraint 2)} \\ x_1 + 2x_2 &\leq 40 \quad \text{(Constraint 3)} \\ x_1, x_2 &\geq 0 \quad \text{(Non-negativity)} \end{aligned} \][/tex]

Before we proceed, let's address the inequalities to convert them into standard form:
- The second constraint, [tex]\(4x_1 + 3x_2 > 60\)[/tex], can be rewritten as [tex]\(-4x_1 - 3x_2 \leq -60\)[/tex].
- The third constraint, [tex]\(x_1 + 2x_2 \leq 40\)[/tex], remains as is.

Now, let's summarize these constraints in the standard form compatible with optimization techniques:

### Constraints in Standard Form:
[tex]\[ \begin{aligned} 3x_1 + x_2 &= 30 \quad \text{(Equality Constraint)} \\ -4x_1 - 3x_2 &\leq -60 \quad \text{(Inequality Constraint 1)} \\ x_1 + 2x_2 &\leq 40 \quad \text{(Inequality Constraint 2)} \\ x_1, x_2 &\geq 0 \quad \text{(Bounds)} \end{aligned} \][/tex]

Given these constraints and the objective function, we can solve the optimization problem.

### Solution:

After solving the problem step-by-step using the appropriate linear programming methods, we find that the optimal solution for the decision variables is:
[tex]\[ x_1 = 4 \][/tex]
[tex]\[ x_2 = 18 \][/tex]

Substituting these values back into the objective function yields:
[tex]\[ z = 4(4) + 18 = 16 + 18 = 34 \][/tex]

Thus, the minimized value of the objective function [tex]\( z \)[/tex] is:
[tex]\[ z = 34 \][/tex]

### Conclusion:

The optimal solution to the given linear programming problem is:
[tex]\[ x_1 = 4 \][/tex]
[tex]\[ x_2 = 18 \][/tex]

And the minimized value of [tex]\( z \)[/tex] is:
[tex]\[ z = 34 \][/tex]

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