Question

Решите систему методом подстановки:
3х-у=-1
-х+2у=7
Напишите подробное решение!

Answer 1

$\left \{ {{3x-y=-1} \atop {-x+2y=7}} \right.\\\\\left \{ {{y=3x+1} \atop {-x+2*(3x+1)=7}} \right.\\\\\left \{ {{y=3x+1} \atop {-x+6x+2=7}} \right.\\\\\left \{ {{y=3x+1} \atop {5x=7-2}} \right.\\\\\left \{ {{y=3x+1} \atop {5x=5}} \right.\\\\\left \{ {{x=1} \atop {y=3*1+1}} \right.\\\\\left \{ {{x=1} \atop {y=4}} \right.\\\\Otvet:\boxed{(1;4)}$