Question

Знайти знаменник геометричної прогресії (bn), якщо b10 = 11, b12 = 99.

Answer 1

$\displaystyle\bf\\\left \{ {{b_{12} =99} \atop {b_{10}=11 }} \right. \\\\\\:\left \{ {{b_{1} \cdot q^{11} =99} \atop {b_{1}\cdot q^{9} =11 }} \right. \\--------\\q^{2} =9\\\\q_{1,2}=\pm \ \sqrt{9}=\pm \ 3$