b₄ = 36;
b₆ = 4.
q - ?
b₄ = b₁q³
b₆ = b₁q⁵
\frac{ b_{6}}{b_{4}}= \frac{b_{1}q^{5}}{b_{1}q^{3}}= q^{2}
q^{2}= \frac{4}{36}= \frac{1}{9}
q_{1} = \sqrt{ \frac{1}{9} }= \frac{1}{3}
q_{2}=- \frac{1}{3}
