5*9分之4+9*13分之4+13*17分之4+.101*105分之4=?简便方法!送分!_数学解答

5*9分之4+9*13分之4+13*17分之4+.101*105分之4=?简便方法!送分!

人气：364 ℃　时间：2020-05-21 03:13:21

解答

1/(5*9)+1/(9*13)+...+1/(101*105)=(1/4)*(1/5-1/9)+(1/4)*(1/9-1/13)+...+(1/4)*(1/101-1/105)=(1/4)*(1/5)-(1/4)*(1/9)+(1/4)*(1/9)-(1/9)*(1/13)+...+(1/4)*(1/101)-(1/4)*(1/105)=(1/4)*(1/5)-(1/4)*(1/105)=(1/...