Question

СРОЧНО ПЖ!!!! Дано: (Bn)- ГП b1= -1 q=3 Найти b7= S6=

Answer 1

$b_{1}=-1\\\\q=3\\\\b_{7}=b_{1}*q^{6}=-1* 3^{6}=-1*729=-729\\\\S_{6}=\frac{b_{1}*(q^{6}-1)}{q-1}=\frac{-1*(3^{6}-1) }{3-1} =\frac{-1*(729-1)}{2}=\frac{-728}{2}=- 364$