Question

Решите систему уравнений методом подстановки:
$left { {{y-2x=1} atop {12x-y=9}} right.$

Answer 1

$y = 2x+1\ 12x - (2x+1) = 9 \ 10x-1 = 9\ 10x = 10\ x=1\ y = 2cdot1+1 = 3\ \ left { {{x=1} atop {y=3}} right.$

Answer 2

$left { {{y-2x=1} atop {12x-y=9}} right.$
$left { {{y=2x+1} atop {12x-y=9}} right.$
$left { {{y=2x+1} atop {12x-(2x+1)=9}} right.$
$left { {{y=2x+1} atop {10x-10=0}} right.$
$left { {{y=2x+1} atop {x=1}} right.$
$left { {{y=3} atop {x=1}} right.$
Ответ:(1;3)