Question

пожалуйста помогите с решением​

Answer 1

2)

$\left \{ {{3(x-1)+4(y+1)=-1} \atop {4(x+1)-3(y-1)=21}} \right.\\\\\left \{ {{3x-3+4y+4=-1} \atop {4x+4-3y+3=21}} \right.\\\\\left \{ {{3x+4y+1=-1} \atop {4x-3y+7=21}} \right.\\\\\left \{ {{3x+4y=-2|*3} \atop {4x-3y=14|*4}} \right. \\\\+\left \{ {{9x+12y=-6} \atop {16x-12y=56}} \right.\\25x = 50\\x = 2\\\\\left \{ {{x=2} \atop {3x+4y=-2}} \right.\\\\\left \{ {{x=2} \atop {6+4y=-2}} \right.\\\\\left \{ {{x=2} \atop {4y=-8}} \right.\\\\\left \{ {{x=2} \atop {y=-2}} \right.$

Ответ: (2; -2)

4)

$\left \{ {{5(3x-y) - 4(4x-2y)=5} \atop {3(2x+y)-2(x+4y)=-13}} \right.\\\\\left \{ {{15x-5y-16x+8y=5} \atop {6x+3y-2x-8y=-13}} \right.\\\\\left \{ {{-x+3y=5|*4} \atop {4x-5y=-13}} \right.\\ \\+\left \{ {{-4x+12y=20} \atop {4x-5y=-13}} \right.\\7y=7\\y = 1\\\\\left \{ {{y=1} \atop {-x+3y=5}} \right.\\\\\left \{ {{y=1} \atop {-x+3=5}} \right.\\ \\\left \{ {{y=1} \atop {-x=2}} \right.\\\\\left \{ {{x=-2} \atop {y=1}} \right.$

Ответ: (-2; 1)