分数计算（提示：用乘法分配律拆项)(228/123+229/234+230/345)×(229/234+230/345+231/456)-(228/123+229/234+230/345+231/456)×（229/234+230/345)

Question

分数计算（提示：用乘法分配律拆项)
(228/123+229/234+230/345)×(229/234+230/345+231/456)-(228/123+229/234+230/345+231/456)×（229/234+230/345)

Answer 1

令228/123+229/234+230/345+231/456=a
原式
=(a-231/456)(a-228/123)-a(a-228/123-231/456)
=a²-231a/456-228a/123+231/456×228/123-a²+228a/123+231a/456
=231/456×228/123
=77/82