PROGRESSIYaI ARIFMETIKI

PROGRESSIYaI ARIFMETIKI, paydarpayi odadhoi a,, a₂, d_p, ki har yak uzvi on aa uzvi peshoyanda- ash dar natijap jam namudanp yagon adadi doimin (d) hosnl meshavad; d–ro f a r q i P. a. menomand (mae., 2, 7, 12, 17, 22, 27, d = 5). Agar d > 0 boshad, P. a. afzunshavanda va agar d <0 boshad, P. a. kamshavanda me boshad. Uzvi u mumii P. a. tavas- suti formulai a_p = a_i + d(n—il); dosili jami p uzvi avvalp P. &. aa ru|I formulai S* = -i. (ai + a_n) disob karda meshavad.

I. Ismatov.