由题意得:A={(x,y)|y=3x+1,x∈N},B={(x,y)|y=a(x2-x+1),x∈N},假设存在正整数a,使得A∩B≠?,即关于x的方程a(x2-x+1)=3x+1有自然数解∵x2-x+1>0,∴a= 3x+1 x2?x+1 ∵a为正整数,∴3x+1≥x2-x+1,解得0≤x≤4,∵x∈N,x可取0,1,2,3,4.代入验证可得,当x=0或x=4时,a=1;当x=1时,a=4.∴a=1或a=4.所以存在正整数a为1或4时,使得A∩B≠?.