В геометрической прогрессии b₁+b₅=17, b₂+b₆=34. Найти b₁ ,

Question

В геометрической прогрессии b₁+b₅=17, b₂+b₆=34. Найти b₁ ,

Answer 1

B2 = b1 ·q
b6 = b5 ·q

b1 + b5 =17
b1·q + b5·q = 34
q·(b1 + b5) = 34
q = 34 :17 = 2
b5 = b1 · q^4 = 16b1
b1 + 16b1 = 17
17b1 = 17
b1 = 1