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Consider the LPP: Minimize Z=x+2yZ = x + 2y subject to 2x+y≥32x + y \geq 3, x+2y≥6x + 2y \geq 6, x,y≥0x, y \geq 0. The optimal feasible solution occurs at

Solution

✅ Correct Option: 4

The problem is to minimize Z=x+2yZ = x + 2y subject to 2x+y≥32x + y \geq 3, x+2y≥6x + 2y \geq 6, and x,y≥0x, y \geq 0.

In Linear Programming, the optimal solution always occurs at corner points of the feasible region.


Finding the corner points by determining where the constraints intersect with the axes:

For constraint 2x+y=32x + y = 3:

  • When x=0x = 0: y=3y = 3 → Point (0,3)(0, 3)
  • When y=0y = 0: x=1.5x = 1.5 → Point (1.5,0)(1.5, 0)

For constraint x+2y=6x + 2y = 6:

  • When x=0x = 0: y=3y = 3 → Point (0,3)(0, 3)
  • When y=0y = 0: x=6x = 6 → Point (6,0)(6, 0)

Both constraints pass through (0,3)(0, 3).


Checking feasibility of (0,3)(0, 3):

2(0)+3=3≥32(0) + 3 = 3 \geq 3 ✓

0+2(3)=6≥60 + 2(3) = 6 \geq 6 ✓

x=0≥0x = 0 \geq 0, y=3≥0y = 3 \geq 0 ✓

Point (0,3)(0, 3) is feasible.


Checking feasibility of (6,0)(6, 0):

2(6)+0=12≥32(6) + 0 = 12 \geq 3 ✓

6+2(0)=6≥66 + 2(0) = 6 \geq 6 ✓

x=6≥0x = 6 \geq 0, y=0≥0y = 0 \geq 0 ✓

Point (6,0)(6, 0) is feasible.


Calculating the objective function at each corner point:

At (0,3)(0, 3):

Z=0+2(3)Z = 0 + 2(3)

Z=6Z = 6

At (6,0)(6, 0):

Z=6+2(0)Z = 6 + 2(0)

Z=6Z = 6


Both points give the same value Z=6Z = 6. This occurs because the objective function line x+2y=6x + 2y = 6 is parallel to constraint x+2y=6x + 2y = 6.

Every point on the line segment from (0,3)(0, 3) to (6,0)(6, 0) gives Z=6Z = 6, resulting in multiple optimal solutions.

Therefore, the optimal feasible solution occurs at both (6,0)(6, 0) and (0,3)(0, 3) with minimum value Z=6Z = 6.

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