Предмет: Алгебра, автор: ЕлизаветаXD

Дана арифметическая прогрессия: 3, 7, 11, … Найдите сумму первых пяти её членов.

Ответы

Автор ответа: Grim

0

1 член прогрессии 3, второй 7.
Разность прогрессии равна 7-3=4
1, 2, 3 члены уже имеются.
4 член равен 11+4=15
5 член равен 15+4=19
Сумма 5 членов равна 3+7+11+15+19=55

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