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The corner points of the feasible region of a LPP with the constraints x+2y≤40x + 2y \leq 40, 3x+y≥303x + y \geq 30, 4x+3y≥604x + 3y \geq 60, x,y≥0x, y \geq 0 are

Solution

✅ Correct Option: 4

We need to find all corner points of the region satisfying all constraints simultaneously:

x+2y≤40x + 2y \leq 40

3x+y≥303x + y \geq 30

4x+3y≥604x + 3y \geq 60

x≥0, y≥0x \geq 0,\ y \geq 0

Corner points occur where the boundary lines intersect. We find all candidate intersections and check if they satisfy every constraint.


Intersection of 3x+y=303x + y = 30 and 4x+3y=604x + 3y = 60

From the first equation: y=30−3xy = 30 - 3x

Substituting into the second:

4x+3(30−3x)=604x + 3(30 - 3x) = 60

4x+90−9x=604x + 90 - 9x = 60

−5x=−30-5x = -30

x=6,y=30−18=12x = 6, \quad y = 30 - 18 = 12

Candidate point: (6,12)(6, 12)

Check: 6+2(12)=30≤406 + 2(12) = 30 \leq 40 ✓ | 3(6)+12=30≥303(6) + 12 = 30 \geq 30 ✓ | 4(6)+3(12)=60≥604(6) + 3(12) = 60 \geq 60 ✓

(6,12)(6, 12) is feasible. ✅


Intersection of x+2y=40x + 2y = 40 and 4x+3y=604x + 3y = 60

From the first equation: x=40−2yx = 40 - 2y

Substituting into the second:

4(40−2y)+3y=604(40 - 2y) + 3y = 60

160−8y+3y=60160 - 8y + 3y = 60

−5y=−100-5y = -100

x=0,y=20x = 0, \quad y = 20

Candidate point: (0,20)(0, 20)

Check: 3(0)+20=20≥303(0) + 20 = 20 \geq 30? ❌

(0,20)(0, 20) is not feasible.


Intersection of x+2y=40x + 2y = 40 and 3x+y=303x + y = 30

From the second equation: y=30−3xy = 30 - 3x

Substituting into the first:

x+2(30−3x)=40x + 2(30 - 3x) = 40

x+60−6x=40x + 60 - 6x = 40

−5x=−20-5x = -20

x=4,y=30−12=18x = 4, \quad y = 30 - 12 = 18

Candidate point: (4,18)(4, 18)

Check: 4+2(18)=40≤404 + 2(18) = 40 \leq 40 ✓ | 3(4)+18=30≥303(4) + 18 = 30 \geq 30 ✓ | 4(4)+3(18)=70≥604(4) + 3(18) = 70 \geq 60 ✓

(4,18)(4, 18) is feasible. ✅


Intersection of 3x+y=303x + y = 30 with the xx-axis (y=0y = 0)

3x=30  ⟹  x=103x = 30 \implies x = 10

Candidate point: (10,0)(10, 0)

Check: 4(10)+3(0)=40≥604(10) + 3(0) = 40 \geq 60? ❌

(10,0)(10, 0) is not feasible.


Intersection of 4x+3y=604x + 3y = 60 with the xx-axis (y=0y = 0)

4x=60  ⟹  x=154x = 60 \implies x = 15

Candidate point: (15,0)(15, 0)

Check: 15+0=15≤4015 + 0 = 15 \leq 40 ✓ | 3(15)+0=45≥303(15) + 0 = 45 \geq 30 ✓ | 4(15)+0=60≥604(15) + 0 = 60 \geq 60 ✓

(15,0)(15, 0) is feasible. ✅


Intersection of x+2y=40x + 2y = 40 with the xx-axis (y=0y = 0)

x=40x = 40

Candidate point: (40,0)(40, 0)

Check: 40≤4040 \leq 40 ✓ | 3(40)=120≥303(40) = 120 \geq 30 ✓ | 4(40)=160≥604(40) = 160 \geq 60 ✓

(40,0)(40, 0) is feasible. ✅


The corner points of the feasible region are:

(4,18),(6,12),(15,0),(40,0)(4, 18), \quad (6, 12), \quad (15, 0), \quad (40, 0)

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