\[b_{1} = 2;\ \ b_{n} = - 54.\]
\[2;b_{1}q;b_{1}q^{2};\ - 54\]
\[2q^{3} = - 54\]
\[q^{3} = - 27\]
\[q = - 3.\]
\[b_{1}q = 2 \cdot ( - 3) = - 6.\]
\[b_{2}q = 2 \cdot ( - 3)^{2} = 18.\]
\[Ответ:числа\ - 6;18.\]