Предмет: Алгебра, автор: abdrazaklibek2

Найти сумму семи первых членов возраст. геометрической прогрессии

b4+b5=24
b6-b4=24
прошу пожалуйста

Simba2017: из второго b6-b4=b1+5d-(b1+3d)=2d=24; d=12

Simba2017: из первого b4+b5=b1+3d+b1+4d=2b1+7d=2b1+7*12=24; b1=24-84=-60

Simba2017: дальше по формуле суммы...

abdrazaklibek2: а формула суммы b1(1-q в n степени)/1-q?

Simba2017: я неверно написала, я арифметическую расписывала

abdrazaklibek2: аааа

Ответы

Автор ответа: ludmilaiapanasenko

Ответ:127

Объяснение: см. решение в файле ниже.

Приложения:

abdrazaklibek2: Спасибо огромное

abdrazaklibek2: Желаю вам всего наилучшего

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Найти сумму семи первых членов возраст. геометрической прогрессии

b4+b5=24
b6-b4=24
прошу пожалуйста