We need to find all corner points of the region satisfying all constraints simultaneously:
x+2y≤40
3x+y≥30
4x+3y≥60
x≥0, y≥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=30 and 4x+3y=60
From the first equation: y=30−3x
Substituting into the second:
4x+3(30−3x)=60
4x+90−9x=60
−5x=−30
x=6,y=30−18=12
Candidate point: (6,12)
Check: 6+2(12)=30≤40 ✓ | 3(6)+12=30≥30 ✓ | 4(6)+3(12)=60≥60 ✓
(6,12) is feasible. ✅
Intersection of x+2y=40 and 4x+3y=60
From the first equation: x=40−2y
Substituting into the second:
4(40−2y)+3y=60
160−8y+3y=60
−5y=−100
x=0,y=20
Candidate point: (0,20)
Check: 3(0)+20=20≥30? ❌
(0,20) is not feasible.
Intersection of x+2y=40 and 3x+y=30
From the second equation: y=30−3x
Substituting into the first:
x+2(30−3x)=40
x+60−6x=40
−5x=−20
x=4,y=30−12=18
Candidate point: (4,18)
Check: 4+2(18)=40≤40 ✓ | 3(4)+18=30≥30 ✓ | 4(4)+3(18)=70≥60 ✓
(4,18) is feasible. ✅
Intersection of 3x+y=30 with the x-axis (y=0)
3x=30⟹x=10
Candidate point: (10,0)
Check: 4(10)+3(0)=40≥60? ❌
(10,0) is not feasible.
Intersection of 4x+3y=60 with the x-axis (y=0)
4x=60⟹x=15
Candidate point: (15,0)
Check: 15+0=15≤40 ✓ | 3(15)+0=45≥30 ✓ | 4(15)+0=60≥60 ✓
(15,0) is feasible. ✅
Intersection of x+2y=40 with the x-axis (y=0)
x=40
Candidate point: (40,0)
Check: 40≤40 ✓ | 3(40)=120≥30 ✓ | 4(40)=160≥60 ✓
(40,0) is feasible. ✅
The corner points of the feasible region are:
(4,18),(6,12),(15,0),(40,0)