Question

помогите пожалуйста ​

Answer 1

Ответ:

6)

    $\left \{ {{x-y=4} \atop {4y+2x=38}} \right. \\x-y=4\\x=y+4\\2(y+4)+4y=38\\2y+8+4y=38\\6y=30\\y=5\\\\x-5=4\\x=9\\\left \{ {{y=5} \atop {x=9}} \right.$

7)

   $\left \{ {{x+2y=7} \atop {3y-5x=4}} \right.\\x+2y=7\\x=7-2y\\3y-5(7-2y)=4\\3y-35+10y=4\\13y=39\\y=3\\\\x=7-2y\\x=7-2(3)\\x=7-6\\x=1\\\left \{ {{x=1} \atop {y=3}} \right.$