Răspuns :
400/81 - 399/81 + 398/81 - .... + 2/81 - 1/81 =
(se grupeaza cate doua)
(400/81 - 399/81) + (398/81 - 987/81) + .... + (2/81 - 1/81) =
400/2=200 (vor fi 200 perechi)
1/81 + 1/81 + ... + 1/81 = 200/81 ----- acesta este raspunsul!
400/81 - 399/81 + 398/81 - .... + 2/81 - 1/81 =
(se grupeaza cate doua)
(400/81 - 399/81) + (398/81 - 987/81) + .... + (2/81 - 1/81) =
400/2=200 (vor fi 200 perechi)
1/81 + 1/81 + ... + 1/81 = 200/81 ----- acesta este raspunsul!