Question

В арифметической прогрессии (an) a8=24,1; а18= -39,1.Найдите разность прогрессии.

Answer 1

$a_{8} = 24,1 ; a_{18} = 39,1\ left { {{a_{8} = 24,1} atop {a_{18} = 39,1}} right. \ left { {{a_{1} + 7d = 24,1} atop {a_{1} + 17d = 39,1}} right. \ -10d = -15 \ d = 1.5$