Question

Пожалуйта решите!!! Даю 20 балов!

Answer 1

Ответ:

$1) 5115\\\\2) 3069$

Объяснение:

$S_n = \frac{b_1(q^n-1)}{q-1}$

$1) b_1 = 5, \ q = 2\\\\S_{10} = \frac{5(2^{10}-1)}{2-1} = 5\cdot1023=5115\\\\\\2) b_1+b_5 = 51, \ b_2+b_6 = 102\\\\b_2+b_6 = b_1q+b_1q^5\\\\b_1 + b_5 = b_1 + b_1q^4\\\\q = \frac{q(b_1 + b_1q^4)}{b_1 + b_1q^4} = \frac{b_2 + b_6}{b_1 + b_5} = \frac{102}{51} = 2\\\\ b_1 + b_5 = b_1 + b_1q^4 = b_1 + b_1\cdot2^4 = b_1(2^4+1) = 51 \Rightarrow b_1 =\frac{51}{17} = 3\\\\S_{10} = \frac{3(2^{10}-1)}{2-1} = 3\cdot1023=3069$