因为,(a²+a+1)-(a²+a-2) = 3 > 0 ,
所以,a²+a+1 > a²+a-2 ;
因为,(1/2)(a²-b²+2)-(1/3)(a²-2b²+1) = (1/6)(a²+b²)+2/3 ≥ 2/3 > 0 ,
所以,(1/2)(a²-b²+2) > (1/3)(a²-2b²+1) .
因为,(a²+a+1)-(a²+a-2) = 3 > 0 ,
所以,a²+a+1 > a²+a-2 ;
因为,(1/2)(a²-b²+2)-(1/3)(a²-2b²+1) = (1/6)(a²+b²)+2/3 ≥ 2/3 > 0 ,
所以,(1/2)(a²-b²+2) > (1/3)(a²-2b²+1) .