Rozwiązanie:
[tex]a_{2}=8\\a_{7}=\frac{1}{4}\\q^{5}=\frac{a_{7}}{a_{2}} =\frac{\frac{1}{4} }{8} =\frac{1}{32}\\q=\sqrt[5]{\frac{1}{32} } =\frac{1}{2}\\a_{1}=\frac{8}{q}=\frac{8}{\frac{1}{2} } =16\\S_{5}=16*\frac{1-(\frac{1}{2} )^{5}}{1-\frac{1}{2} } =16*\frac{\frac{31}{32} }{\frac{1}{2} } =31[/tex]
