The four constraints are:
- x−2y≥0
- 2x−y≤−4
- x≥0
- y≥0
The solution set contains points that satisfy all four constraints simultaneously.
From constraint 1: x−2y≥0
x≥2y ... (A)
From constraint 2: 2x−y≤−4
−y≤−4−2x
y≥2x+4 ... (B)
Constraints 3 and 4 indicate the first quadrant.
From (B): y≥2x+4
Substituting into (A):
x≥2y
x≥2(2x+4)
x≥4x+8
−3x≥8
x≤−38
The constraints require:
x≤−38 (approximately −2.67)
AND
x≥0 (from constraint 3)
These cannot be satisfied simultaneously. No point can have x≤−38 and x≥0 at the same time.
Since no point satisfies all four constraints, the solution set is empty.
Therefore, the solution set is ϕ.