1×2×3/1加2×3×4/1加……加20×21×22/1 用简算,

问题描述:

1×2×3/1加2×3×4/1加……加20×21×22/1 用简算,

1×2×3/1加2×3×4/1加……加20×21×22/1
=(1×2/1-2×3/1加2×3/1-3×4/1加……加20×21/1-21×22/1)÷2
=(1×2/1-21×22/1)÷2
=(2/1-462/1)÷2
=462/230÷2
=462/115我的试卷答案上是115分之462,没过程462/115就是462分之115,你把分子、分母说反了哦,对不起,试卷上是462分之115462/115就是462分之115