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)