Solve the following problems using simplex methods.

a. [tex]\operatorname{Max} Z=3x_1+5x_2[/tex]

Subject to:
[tex]
\begin{array}{c}
x_2 \leq 6 \\
3x_1+2x_2 \leq 18 \\
x_1, x_2 \geq 0
\end{array}
[/tex]



Answer :

Let's solve the linear programming problem using the simplex method step-by-step.

We are given the objective function:
[tex]\[ \operatorname{Max} Z = 3x_1 + 5x_2 \][/tex]

subject to the constraints:
[tex]\[ \begin{aligned} 1. &\ x_2 \leq 6 \\ 2. &\ 3x_1 + 2x_2 \leq 18 \\ 3. &\ x_1, x_2 \geq 0 \end{aligned} \][/tex]

### Step 1: Convert Inequalities to Equalities
We introduce slack variables [tex]\(s_1\)[/tex] and [tex]\(s_2\)[/tex] to convert the inequalities into equalities:

1. [tex]\(x_2 + s_1 = 6\)[/tex]
2. [tex]\(3x_1 + 2x_2 + s_2 = 18\)[/tex]

Where [tex]\(s_1, s_2 \geq 0\)[/tex].

### Step 2: Set Up the Initial Simplex Tableau

[tex]\[ \begin{array}{c|cccc|c} & x_1 & x_2 & s_1 & s_2 & \text{RHS} \\ \hline \text{Constraint 1} & 0 & 1 & 1 & 0 & 6 \\ \text{Constraint 2} & 3 & 2 & 0 & 1 & 18 \\ \hline \text{Objective Function} & -3 & -5 & 0 & 0 & 0 \\ \end{array} \][/tex]

### Step 3: Perform Simplex Algorithm Iterations

#### Iteration 1:

Identify the entering variable (most negative in the objective row):
- Entering variable: [tex]\(x_2\)[/tex] (coefficient -5)

Identify the leaving variable (minimum ratio test):
- Ratios: [tex]\(\frac{6}{1} = 6\)[/tex], [tex]\(\frac{18}{2} = 9\)[/tex]
- Leaving variable: [tex]\(s_1\)[/tex]

Pivot on the element in the [tex]\(x_2\)[/tex] column and [tex]\(s_1\)[/tex] row.

Update the tableau:

[tex]\[ \begin{array}{c|cccc|c} & x_1 & x_2 & s_1 & s_2 & \text{RHS} \\ \hline \text{Row 1 (New Basis)} & 0 & 1 & 1 & 0 & 6 \\ \text{Row 2} & 3 & 2 & 0 & 1 & 18 \\ \hline \text{Objective Function} & -3 & 0 & 5 & 0 & 30 \\ \end{array} \][/tex]

#### Iteration 2:

Identify the entering variable (most negative in the objective row):
- Entering variable: [tex]\(x_1\)[/tex] (coefficient -3)

Identify the leaving variable (minimum ratio test):
- Ratios: [tex]\(\frac{18}{3} = 6\)[/tex]

Pivot on the element in the [tex]\(x_1\)[/tex] column and the second row:

Update the tableau:

[tex]\[ \begin{array}{c|cccc|c} & x_1 & x_2 & s_1 & s_2 & \text{RHS} \\ \hline \text{Row 1} & 0 & 1 & 1 & 0 & 6 \\ \text{Row 2 (New Basis)} & 1 & 2/3 & 0 & 1/3 & 6 \\ \hline \text{Objective Function} & 0 & 1 & 5 & 1 & 36 \\ \end{array} \][/tex]

The objective row has no more negative coefficients, which means we have reached the optimal solution.

### Step 4: Extract the Solution

From the final tableau:
- [tex]\(x_1 = 2\)[/tex]
- [tex]\(x_2 = 6\)[/tex]

The maximum value of [tex]\(Z\)[/tex] is:
[tex]\[ Z = 3(2) + 5(6) = 6 + 30 = 36 \][/tex]

### Conclusion
The optimal solution is:
[tex]\[ x_1 = 2, \quad x_2 = 6 \][/tex]
The maximum value of the objective function is:
[tex]\[ Z = 36 \][/tex]