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Module 3 - The Simplex Method

Consider the following linear program: x 1
+2x 2
x 1
+5x 2
≤10
2x 1
+6x 2
≤16
x 1
,x 2
≥0
Write the problem in standard form.
1.1 How many variables will be set equal to zero in a basic solution for this problem?
1.2 Find all the basic solutions, and indicate which are also feasible.
1.3 Find the optimal solution by computing the value of each basic feasible solution.
Please show all steps, how to do row operations and first iteration.
Thank you.

User Mike Eason
by
8.1k points

1 Answer

3 votes

Answer:

z=10

Explanation:

To write the given linear program in standard form, we need to convert the inequalities into equalities and introduce slack variables.

The original linear program:

Maximize: Z = x1 + 2x2

Subject to:

x1 + 2x2 ≤ 10

2x1 + 6x2 ≤ 16

x1, x2 ≥ 0

To convert the inequalities into equalities, we introduce slack variables:

Let s1 and s2 be the slack variables for the first and second constraints, respectively.

The linear program in standard form becomes:

Maximize: Z = x1 + 2x2

Subject to:

x1 + 2x2 + s1 = 10

2x1 + 6x2 + s2 = 16

x1, x2, s1, s2 ≥ 0

1.1 In a basic solution, the number of variables set equal to zero is equal to the number of constraints. In this case, there are 2 constraints, so 2 variables will be set equal to zero in a basic solution.

1.2 To find all the basic solutions, we need to set the slack variables (s1 and s2) equal to zero and solve the system of equations.

Setting s1 = 0 and s2 = 0, we have:

x1 + 2x2 = 10

2x1 + 6x2 = 16

Solving these equations, we can use row operations to eliminate x1:

Row 2 - 2 * Row 1:

0x1 + 2x2 = 16 - 2 * 10

2x2 = -4

x2 = -2

Substituting x2 = -2 into the first equation:

x1 + 2(-2) = 10

x1 - 4 = 10

x1 = 14

So, the basic solution is (x1, x2) = (14, -2).

1.3 To find the optimal solution, we need to compute the value of each basic feasible solution.

Substituting the basic solution (14, -2) into the objective function:

Z = 14 + 2(-2)

Z = 14 - 4

Z = 10

Therefore, the optimal solution is Z = 10.

Note: This is just the first iteration. If there are more variables and constraints, the process may involve multiple iterations using the simplex method to find the optimal solution

User Gabomgp
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