来自金晓龙的问题
a-2a+3a-4a+5a-6a+...+99a-100a
a-2a+3a-4a+5a-6a+...+99a-100a
1回答
2020-03-27 01:05
a-2a+3a-4a+5a-6a+...+99a-100a
a-2a+3a-4a+5a-6a+...+99a-100a
原式=(a-2a)+(3a-4a)+……+(99a-100a)
=-a×50
=-50a