Question

4. Чему равна сумма: 1/(1*3)+1/(3*5)+1/(5*7)+⋯+1/(99*101)

Answer 1

1*3;3*5;5*7;7*9;9*11
11*13.....................
21...............
31..............
41...........
(10)⇒
(5*10)/101=50/101