Let D: (X-2) 178; + (Y-1) 178; ≤ 1, compare the sizes of I & # 8321; = ∫∫ D (x + y) d σ, I &; = ∫∫ D (x + y) & # 178; D σ, I & # 8323; = ∫∫ D (x + y) & # 179; D σ
This double integral should be solved by using the properties of double integral, mainly by using monotonicity