首页 > 留学知识库

问题: 求和

1/(1+3)+1/(5+7) +1/(7+9)......+1/(99+101)求和

解答:

 1/(1*3) + 1/(3*5) + 1/(5*7) + ... + 1/(99+101)
= (1/2)[(3-1)/(1*3) + (5-3)/(3*5) + ... + (101-99)/(99+101)]
= (1/2)[(1-1/3) + (1/3-1/5) + ...+ (1/99-1/101)]
= (1/2)(1-1/101)
= 50/101