Question

25 БАЛЛОВ!
методом подстановки

Answer 1

$\left \{ {{x+2y=12} \atop {2x-3y=-18}} \right.\\\\ \left \{ {{x=12-2y} \atop {2(12-2y)-3y=-18}} \right.\\\\ \left \{ {{x=12-2y} \atop {24-4y-3y=-18}} \right.\\\\ \left \{ {{x=12-2y} \atop {-7y=-42}} \right. \\\\ \left \{ {{x=12-2*6} \atop {y=6}} \right.\\\\ \left \{ {{x=0} \atop {y=6}} \right.$
Ответ : (0 ; 6)

$\left \{ {{6(x+y)=5-(2x+y)} \atop {3x-2y=-3y-3}} \right. \\\\ \left \{ {{6x+6y=5-2x-y} \atop {3x+y=-3}} \right. \\\\ \left \{ {{8x+7y=5} \atop {y=-3x-3}} \right. \\\\ \left \{ {{8x+7(-3x-3)=5} \atop {y=-3x-3}} \right.\\\\ \left \{ {{8x-21x-21=5} \atop {y=-3x-3}} \right.\\\\ \left \{ {{-13x=26} \atop {y=-3x-3}} \right.\\\\ \left \{ {x=-2} \atop {y=-3*(-2)-3}} \right. \\\\ \left \{ {{x=-2} \atop {y=3}} \right.$
Ответ: (- 2 ; 3)