1、方程式解法:
令a=123456789, b=987654321
则A=a*b, B=(a-1)*(b+1)
那么B=a*b-b+a-1
=A +(a-(b+1))
>A
所以B>A
2、算数式解法:
A-B=987654321X123456789-987654322X123456788
=(987654322-1)X123456789-987654322X123456788
=987654322X(123456789-123456788)-123456789
=987654322-123456789>0
∴A>B