设平面闭区域D由x=0,y=0,x+y=,x+y=1所围成,I 1 =[ln(x+y)] 3 dxdy,I 2 =(x+y) 3 dxdy,I 3 =
I 1 <I 2 <I 3
I 1 <I 3 <I 2
I 3 <I 2 <I 1
I 3 <I 1 <I 2
解析:在积分区域D内,有