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)