2\1+6\5+12\11+20\19+30\29...+9900\9899
问题描述：
2\1+6\5+12\11+20\19+30\29...+9900\9899
答
2/1+6/5+12/11+20/19+30/29····9702/9701+9900/9899=99-(2/1+6/1+12/1+20/1+30/1+……+9702/1+9900/1）=99-（1-2/1+2/1-3/1+3/1-4/1+4/1-5/1+5/1-6/1+……+98/1-99/1+99/1-100/1）=99-（1-100/1）=98又100/1=98....