Question

Геометрическая прогрессия.Даю 50 баллов
Срочноооооооооооооо!!!!!!!!!!!!

Answer 1

$q = \frac{b_n}{b_{n-1}} \\ q = \frac{ \sqrt{7} }{7} \\ \\ b_1 = \frac{b_n}{ {q}^{n - 1} } \\ b_1 = \frac{ \frac{1}{162} }{ { ( - \frac{1}{3} )}^{5 - 1} } \\ b_1 = \frac{ \frac{1}{162} }{ { \frac{1}{3} }^{4} } \\ b_1 = \frac{ \frac{1}{162} }{ { \frac{1}{81} }} \\ b_1 = 81 \times \frac{1}{162} \\ b_1 = \frac{1}{2}$

$S = \frac{b_1(q^{n} - 1) }{ {q}^{n} - 1 } \\ b_1 = \frac{ \frac{1}{8} }{ \frac{1}{2} } \\ b_1 = \frac{2}{8} \\ b_1 = \frac{1}{4} \\ \\S = \frac{ \frac{1}{4} ( \frac{1}{2} ^{5} - 1) }{ { \frac{1}{2} }^{5} - 1 } \\ S = \frac{ \frac{1}{4} ( \frac{1}{32} - 1) }{ { \frac{1}{32} } - 1 } \\ S = \frac{ - \frac{1}{4} \times \frac{31}{32} }{ { - \frac{31}{32} } } \\ S = \frac{1}{4}$