Translate the following LPP in the standard form Minimize Z = 5x1 + 7x2 Subject to x1 + x2 ≤ 8, 3x1 + 4x2 ≥ 3, 6x1 + 7x2 ≥ 5 and x1, x2 ≥ 0.

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Understand the Problem

The question is asking to translate given linear programming problems (LPP) into their standard forms, which involves setting an objective function and defining the constraints appropriately.

Answer

Minimize $$ Z = 5x_1 + 7x_2 $$; Maximize $$ Z = 4x_1 + 2x_2 + 6x_3 $$; with appropriate constraints and non-negativity requirements.
Answer for screen readers

For the first LPP:

Minimize $$ Z = 5x_1 + 7x_2 $$ Subject to:

  1. $$ x_1 + x_2 + s_1 = 8 $$
  2. $$ 3x_1 + 4x_2 - s_2 = 3 $$
  3. $$ 6x_1 + 7x_2 - s_3 = 5 $$
  4. $$ x_1, x_2, s_1, s_2, s_3 \geq 0 $$

For the second LPP:

Maximize $$ Z = 4x_1 + 2x_2 + 6x_3 $$ Subject to:

  1. $$ 2x_1 + 3x_2 + 2x_3 - s_1 = 6 $$
  2. $$ 3x_1 + 4x_2 = 8 $$
  3. $$ 6x_1 - 4x_2 + x_3 + s_2 = 10 $$
  4. $$ x_1, x_2, x_3, s_1, s_2 \geq 0 $$

Steps to Solve

  1. Standard Form for Minimization Problem

For the first linear programming problem, we need to translate it into standard form. Standard form for a minimization problem requires all constraints to be in the form of equalities.

  • Objective function: $$ Z = 5x_1 + 7x_2 $$
  1. Convert Inequalities to Equalities

We need to convert the inequalities into equations by adding slack or surplus variables.

  • Constraints:
  1. From the constraint ( x_1 + x_2 \leq 8 ):

    • Introduce slack variable ( s_1 ): $$ x_1 + x_2 + s_1 = 8 $$
  2. From the constraint ( 3x_1 + 4x_2 \geq 3 ):

    • Introduce surplus variable ( s_2 ): $$ 3x_1 + 4x_2 - s_2 = 3 $$
  3. From the constraint ( 6x_1 + 7x_2 \geq 5 ):

    • Introduce surplus variable ( s_3 ): $$ 6x_1 + 7x_2 - s_3 = 5 $$
  1. Non-negativity Constraints

The requirements ( x_1, x_2 \geq 0 ) remain the same. It also applies to the added slack and surplus variables ( s_1, s_2, s_3 \geq 0 ).

  1. Final Standard Form

Thus, the complete standard form for this LPP is:

  • Objective Function: $$ \text{Minimize } Z = 5x_1 + 7x_2 $$

  • Subject to:

  1. $$ x_1 + x_2 + s_1 = 8 $$
  2. $$ 3x_1 + 4x_2 - s_2 = 3 $$
  3. $$ 6x_1 + 7x_2 - s_3 = 5 $$
  4. $$ x_1, x_2, s_1, s_2, s_3 \geq 0 $$
  1. Translate Second LPP to Standard Form

For the second linear programming problem, we similarly need to rewrite it for maximization.

  • Objective function: $$ Z = 4x_1 + 2x_2 + 6x_3 $$
  1. Convert Inequalities to Equalities
  • Constraints:
  1. From ( 2x_1 + 3x_2 + 2x_3 \geq 6 ):

    • Introduce surplus variable ( s_1 ): $$ 2x_1 + 3x_2 + 2x_3 - s_1 = 6 $$
  2. From ( 3x_1 + 4x_2 = 8 ):

    • This already fits an equality form.
  3. From ( 6x_1 - 4x_2 + x_3 \leq 10 ):

    • Introduce slack variable ( s_2 ): $$ 6x_1 - 4x_2 + x_3 + s_2 = 10 $$

For the first LPP:

Minimize $$ Z = 5x_1 + 7x_2 $$ Subject to:

  1. $$ x_1 + x_2 + s_1 = 8 $$
  2. $$ 3x_1 + 4x_2 - s_2 = 3 $$
  3. $$ 6x_1 + 7x_2 - s_3 = 5 $$
  4. $$ x_1, x_2, s_1, s_2, s_3 \geq 0 $$

For the second LPP:

Maximize $$ Z = 4x_1 + 2x_2 + 6x_3 $$ Subject to:

  1. $$ 2x_1 + 3x_2 + 2x_3 - s_1 = 6 $$
  2. $$ 3x_1 + 4x_2 = 8 $$
  3. $$ 6x_1 - 4x_2 + x_3 + s_2 = 10 $$
  4. $$ x_1, x_2, x_3, s_1, s_2 \geq 0 $$

More Information

Standard form LPPs require converting inequalities into equalities using slack or surplus variables. The objective function for minimization wants to find the minimum value, while maximization seeks the highest value.

Tips

  • Forgetting to include non-negativity constraints for slack or surplus variables.
  • Misplacing or misreading the direction of inequalities when converting to equalities.

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