Question

геометрические прогресия ​

Answer 1

$\left \{ {{b_{6}=5} \atop {b_{3}=40}} \right.\\\\:\left \{ {{b_{1} *q^{5}=5 } \atop {b_{1}*q^{2}=40}} \right.\\ ------\\q^{3}=\frac{1}{8}\\\\q=\frac{1}{2}\\\\b_{n} =b_{1}*q^{n-1}\\\\b_{n}=b_{n-1}*q\\\\b_{7} =b_{6}*q=5*\frac{1}{2}=2,5$