Concept:The constraints define a feasible region in the first quadrant bounded by the lines ∣x−y∣=1.Explanation:The inequality ∣x−y∣≤1 means −1≤x−y≤1.This gives two boundary lines: x−y=1 and x−y=−1.With x,y≥0, the region lies in the first quadrant.The strip between x−y=1 and x−y=−1 extends infinitely along the positive x and y directions.So the feasible region has no upper bound and is not closed.