Concept:The feasible region is the set of points satisfying all given inequalities simultaneously.
Explanation:For
2x+3y≤18, the origin satisfies
0≤18, so the region lies on the origin side of this line.
For
x+y≥10, the origin does not satisfy
0≥10, so the region lies on the non-origin side.
Now, on the line
x+y=10, express
2x+3y=2x+3(10−x)=30−x.
For
0≤x≤10, the minimum value of
30−x is
20, which is greater than
18.
Hence, no point in the first quadrant can satisfy both
2x+3y≤18 and
x+y≥10.
Answer:The feasible region is empty, so it is a null set.
Correct option: D. null set.