6/1*7 - 6/7*13 - 6/13*19 – 6/19*25-…-6/97*103选项 A.433/567 B.532/653 C.522/721 D. 436/673

问题描述:

6/1*7 - 6/7*13 - 6/13*19 – 6/19*25-…-6/97*103
选项 A.433/567 B.532/653 C.522/721 D. 436/673

6/1*7=1-1/7
6/7*13=1/7-1/13
……
6/97*103=1/97-1/103
6/1*7 - 6/7*13 - 6/13*19 – 6/19*25-…-6/97*103
=1-1/7-(1/7-1/13)-(1/13-1/19)-……-(1/97-1/103)
=1-1/7-1/7+1/103
=5/7+1/103
=522/721
故选C.522/721