Question

Найдите первый член геометрической прогрессии, если b6=9; q = 3

Answer 1

b6 = b1 * 5q

b6 = x * 5*3

x = 15 / 9

x = 5\3

Answer 2

$b_{6} =b_{1} *q^{5}$

$9=b_{1} *3^{5}$

$b_{1}=\frac{3^{2}}{3^{5}} =\frac{9}{243} =\frac{1}{27}$