Question

Пжжж даю много баллл

Answer 1

$1)\left \{ {{a_{1}+a_{5}=20} \atop {a_{2}+a_{3}=17}} \right. \\\\\left \{ {{a_{1} +a_{1}+4d=20} \atop {a_{1}+d+a_{1}+2d=17}} \right.\\\\-\left \{ {{2a_{1}+4d=20 } \atop {2a_{1}+3d=17 }} \right.\\-------\\d=3\\\\2a_{1}+4d=20\\\\a_{1}+2d=10\\\\a_{1}=10-2d=10-2*3=4\\\\Otvet:\boxed{a_{1}=4;d=3}$

$2)\left \{ {{a_{1}+a_{6}=26} \atop {a_{2}+a_{3}=18}} \right.\\\\\left \{ {{a_{1}+a_{1}+5d=26} \atop {a_{1}+d+a_{1}+2d=18}} \right.\\\\-\left \{ {{2a_{1}+5d=26} \atop {2a_{1}+3d=18 }} \right.\\ -------\\2d=8\\d=4\\\\2a_{1}=18-3d=18-3*4=18-12=6\\a_{1}=3\\\\Otvet:\boxed{a_{1}=3;d=4}$

Answer 2

Ответ: во вложении Объяснение: