Question

В геометрической прогрессии b4 = 81, b8 = 729. Найдите b2

Answer 1

$b_8=b_4q^4;$
$729=81q^4;$
$q^4=729/81=9;$
$q^2=3;$
$b_2=b_4/q^2=81/3=27.$