Ответы на вопрос:
1) sn=b₁(q^n -1)/(q-1). 635 =5(2^n -1)/(2-1)⇔127 =2^n -1 ⇔ 2^n =128 ⇔ 2^n =2⁷⇒ n =7. 2) 4088 = 8(2^n -1)/(2-1)⇔511 =2^n -1 ⇔ 2^n =512 ⇔ 2^n =2⁹⇒ n =9. bn =b₁*q^(n-1) ⇒ b₉ =8*2⁸ =2¹¹ =2048. 3) bn =b₁*q^(n-1) ⇒ 243 =1*3^(n-1) ⇔3⁵ =3^(n-1) ⇔5 =n-1 ⇒ n=6. s(6) =1*(3⁶ -1)/(3-1) = (729 - 1)/2 = 728/2 = 364.
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