Предмет: Математика, автор: deroxplaygaming

найти среднее арифметическое двух чисел которые находятся между числами 7 и 448 и вместе с ними составляют геометрическую прогрессию

Ответы

Автор ответа: sergeevaolga5

Ответ:

$70$

Решение:

$(b_n)$ - геометрическая прогрессия

$(b_n)\; \; \; b_1=7;b_4=448\\b_2=?\; b_3=?$

Находим $q$ - знаменатель геометрической прогрессии:

$(b_n)\; \; \; 7;b_2;b_3;448\\\\q^3=448:7\\q^3=64\\q^3=4^3\\q=4$

Находим $b_2$ и $b_3$ :

$b_2=b_1q=7*4=28\\b_3=b_2q=28*4=112$

Находим среднее арифметическое чисел $b_2$ и $b_3$ :

$(b_2+b_3):2=(28+112):2=140:2=70$

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