Ответы на вопрос:
А2 = a1 + d = 145 a15 = a1 + 14d = 80 a15 - a2 = 13d = 80 - 145 = -65 13d = -65 d = -5 a2 = a1 + d 145 = a1 - 5 a1 = 150 a16 = a1 + 15d = 150 + 15*(-5) = 75 s16 = (a1 + a16)*16/2 = (150 + 75) * 8 = 225 * 8 = 1800 ответ: 1800
Популярно: Алгебра
-
katenkaklimcuk25.07.2020 17:46
-
Unicorn47116.06.2021 17:45
-
valiullina1260109.09.2021 08:28
-
sot5806.02.2022 23:08
-
Испан116.06.2021 16:27
-
islom050314.12.2020 19:39
-
lubovsalamatova12.07.2020 14:15
-
CatMyBoss17.04.2022 00:27
-
ZHENYAKIM200806.11.2022 04:11
-
ImperialDragonYT02.08.2022 02:37