ответ: a₈=1/81.
Объяснение:
27; 9; 3; ...
a₁=27 a₂=9
q=a₂/a₁=9/27=1/3.
an=a₁qⁿ⁻¹=1/81
a₁qⁿ⁻¹=1/81
27*(1/3)ⁿ⁻¹=1/3⁴
3³*(1/3)ⁿ⁻¹=1/3⁴ |÷3³
(1/3)ⁿ⁻¹=1/3⁽⁴⁺³⁾
1/3ⁿ⁻¹=1/3⁷
n-1=7
n=8 ⇒
a₈=1/81.
