Question

a)$left { {{y=-3x} atop {5x + 3y = 12}} right.$

Answer 1

Действительное решение нет [x,y] ∈∅

Answer 2

$left { {{y=-3x} atop {5x + 3y = 12}} right. left { {{y=-3x} atop {5x + 3*(-3x) = 12}} right. left { {{y=-3x} atop {5x -9x = 12}} right. \ left { {{y=-3x} atop {-4x = 12}} right. left { {{y=-3x} atop {x =-3}} right. left { {{y=-3*(-3)} atop {x =-3}} right. left { {{y=9} atop {x =-3}} right.$
ответ: (-3;9)