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Which of the region shown in the given figures represents the feasible region bounded by the following constraints?

4x+y≥804x + y \geq 80, 2x+y≥602x + y \geq 60, x+y≤80x + y \leq 80, x≥0x \geq 0, y≥0y \geq 0

Figure for CUET Mathematics 2025 21 May Shift 2 question 21 (Algebra)

Solution

✅ Correct Option: 3

The feasible region satisfies all the given constraints simultaneously: 4x+y≥804x + y \geq 80, 2x+y≥602x + y \geq 60, x+y≤80x + y \leq 80, x≥0x \geq 0, y≥0y \geq 0.


The boundary lines are:

Line 1: 4x+y=804x + y = 80

Line 2: 2x+y=602x + y = 60

Line 3: x+y=80x + y = 80

Lines 4 & 5: x=0x = 0 (y-axis) and y=0y = 0 (x-axis)


For Line 1: 4x+y=804x + y = 80

When x=0x = 0: y=80y = 80 giving point (0,80)(0, 80)

When y=0y = 0: 4x=804x = 80

x=20x = 20 giving point (20,0)(20, 0)


For Line 2: 2x+y=602x + y = 60

When x=0x = 0: y=60y = 60 giving point (0,60)(0, 60)

When y=0y = 0: 2x=602x = 60

x=30x = 30 giving point (30,0)(30, 0)


For Line 3: x+y=80x + y = 80

When x=0x = 0: y=80y = 80 giving point (0,80)(0, 80)

When y=0y = 0: x=80x = 80 giving point (80,0)(80, 0)


Testing the origin (0,0)(0, 0) in each inequality:

For 4x+y≥804x + y \geq 80: 0≥800 \geq 80 is false, so the region is away from origin

For 2x+y≥602x + y \geq 60: 0≥600 \geq 60 is false, so the region is away from origin

For x+y≤80x + y \leq 80: 0≤800 \leq 80 is true, so the region is towards origin

For x≥0x \geq 0 and y≥0y \geq 0: the region is in the first quadrant


The feasible region must be:

  • Above both 4x+y=804x + y = 80 and 2x+y=602x + y = 60
  • Below x+y=80x + y = 80
  • In the first quadrant

Region C satisfies all these conditions. It lies between the two lower lines, stays below the upper line, and remains in the first quadrant.

Region A is below all lines and violates both ≥\geq constraints.

Region B is too low and violates 4x+y≥804x + y \geq 80.

Region D is above x+y=80x + y = 80 and violates x+y≤80x + y \leq 80.


Therefore, the answer is Option 3 (Region C).

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