Question

Решить
а-арифметическая прогрессия
а3*а6=406
а9/а4=2

Answer 1

$\left \{ {{a_{3}*a_{6}=406} \atop {\frac{a_{9} }{a_{4}}=2} \right.\\\\\left \{ {{a_{3}*a_{6}=406} \atop {a_{9}=2a_{4}}} \right.\\\\\left \{ {{(a_{1}+2d)*(a_{1}+5d)=406} \atop {a_{1}+8d=2*(a_{1}+3d)}} \right.\\\\\left \{ {{a_{1}^{2}+5a_{1}d+2a_{1}d+10d^{2}=406} \atop {8d-6d=2a_{1}-a_{1}}} \right.\\\\\left \{ {{a_{1}=2d } \atop {(2d)^{2}+7d*2d+10d^{2}=406}} \right.\\\\\left \{ {{a_{1}=2d } \atop {4d^{2}+14d^{2}+10d^{2}=406}} \right.$

$\left \{ {{a_{1}=2d } \atop {28d^{2}=406 }} \right.\\\\d_{1,2}=\pm\sqrt{\frac{29}{2}}\\\\a_{1,2}=\pm2\sqrt{\frac{29}{2}}$

Answer 2

Объяснение:

решение в приложении