每课必练 21.1x0.99 用递等式计算
问题描述:
每课必练 21.1x0.99 用递等式计算
答
21.1x0.99
=21.1x(1-0.01)
=21.1x1 - 21.1*0.01
=21.1 - 0.211
= 20.889