Question

问一道数学题.速度,在线等待,谢谢了.

Answer 1

19.9-19.8+19.7-19.6+19.5-19.4+……+0.5-0.4+0.3-0.2+0.1

=(19.9-19.8)+(19.7-19.6)+(19.5-19.4)+……+(0.5-0.4)+(0.3-0.2)+0.1

=0.1* (19.9+0.1)/0.2

=10