Question

Решите систему уравнений 6x+7y=7 5y-4x=34

Answer 1

$\left \{ {{6x+7y=7} \atop {5y-4x=34}} \right.\\\\\left \{ {{6x+7y=7}|*2 \atop {-4x+5y=34}|*3} \right.\\\\+\left \{ {{12x+14y=14} \atop {-12x+15y=102}} \right.\\--------\\29y=116\\y=4\\\\6x=7-7y=7-7*4=7-28=-21\\\\x=-21:6=-3,5\\\\Otvet:(-3,5;4)$