Question

. Реши систему уравнений

Answer 1

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Answer 2

$left { {{frac{3}{4}x + frac{1}{2}y = -3 atop {3x - frac{y}{3 }=- 5}} right. \ left { {{3x+2y= -12} atop {9x - y = -15}} right.\ left { {{3x+2y= -12} atop {18x - 2y = -30}} right.$

 

Cложим почленно уравнения последней системы , получаем

21 х = -42

х= - 42 : 21

х= -2

Если х =-2 , то  3 · (-2) - у/ 3 = -5

                            - 6 - у/ 3 = -5

                                - у/3 = -5 + 6

                               -у/3 = 1

                                у= -3

Отвнт : (-2; -3)