Question

Система уравнений 3y+2x=8
y-3x=21

Answer 1

$\left \{ {{3y+2x=8} \atop {y-3x=21}} \right.\\\\ \left \{ {{y=21+3x} \atop {3(21+3x)+2x=8}} \right. \\\\ \left \{ {{y=21+3x} \atop {63+9x+2x=8}} \right. \\\\ \left \{ {{y=21+3x} \atop {11x=-55}} \right.\\\\ \left \{ {{x=-5} \atop {y=21+3*(-5)}} \right. \\\\ \left \{ {{x=-5} \atop {y=6}} \right.$
Ответ : (- 5 ; 6)