Question

В геометрической прогрессии найдите b1, если q=3 и S5=484

Answer 1

q = 3     S₅ = 484     n = 5     b₁ = ?

$S_{5}=\frac{b_{1}*(q^{5}-1)}{q-1}\\\\\frac{b_{1}*(3^{5}-1)}{3-1} =484\\\\b_{1}*(243-1)=484*2\\\\b_{1} =\frac{484*2}{242}=4\\\\b_{1} =4$