Question

3х + 4 y = 2
x -y = 3
Решите систему уравнений

Answer 1

$\left \{ {{3x+4y=2} \atop {x-y=3}} \right. \\\\\left \{ {{3x+4y=2} \atop {x=3+y}} \right. \\\\\left \{ {{3(3+y)+4y=2} \atop {x=3+y}} \right.\\\\\left \{ {{9+3y+4y=2} \atop {x=3+y}} \right.\\\\\left \{ {{3y+4y=2-9} \atop {x=3+y}} \right.\\\\\left \{ {{7y=-7} \atop {x=3+y}} \right.\\\\\left \{ {{y=-1} \atop {x=3+y}} \right.\\\\\left \{ {{y=-1} \atop {x=3+(-1)}} \right.\\\\\left \{ {{y=-1} \atop {x=2}} \right.$

Ответ:  x = 2 ; y = -1