首页 > 留学知识库

问题: (1+1/51)*(1-1/51)*(1+1/52)*(1-1/52)*...*(1+1/152)*

奥赛题

解答:

原式=[1-1/(51*51)]*[1-1/(52*52)]*[1-1/(53*53)]*............*[1-1/(152*152)]
=[(51*51-1)/(51*51)]*[(52*52-1)/(52*52)]*[(53*53-1/(53*53)]*............*[(152*152-1)/(152*152)]
=[(50*52)/(51*51)]*[(51*53)/(52*52)]*[(52*54/(53*53)]*............*[(151*153)/(152*152)]
=50/51*153/152
=75/76