Question

4. Знайдіть суму восьми перших членів геометричної прогресії (bn), якщо b2 = 1, b4= 16​

Answer 1

Ответ:

b1 = √b2 = 1

b3 = √(b2 b4) = √(1 16) = 4

b5 = √(b4 b6) = √(16 b6)

16 = √(b2 b4) = √(1 16) = 4

b6 = (16/b4) = (16/16) = 1

b7 = √(b6 b8) = √(1 b8)

b8 = (b7^2)/b6 = (b7^2)/1

Since we don't know b7, we can't find b8.

Sum of first 8 terms:

b1 + b2 + b3 + ... + b8

= 1 + 1 + 4 + ... + b8

= 1 + 1 + 4 + ... + (b7^2)/1