Question

x+2y=4,
{
-1,5x+y=6
и еще вот это

x-y=-2
{
5x-2y=2

Answer 1

$\left \{ {{x+2y=4} \atop {-1,5x+y=6}} \right.$
$\left \{ {{x = 4-2y} \atop {-1,5x+y=6}} \right.$
-1,5 * (4-2y) + y = 6
-6 + 3y + y = 6
4y = 12
y = 3
$\left \{ {{x=4-2y} \atop {y = 3}} \right.$
x = 4 - 2*3 
x = 4 - 6
x = -2
$\left \{ {{x=-2} \atop {y=3}} \right.$
Ответ: (-2;3)

$\left \{ {{x-y=-2} \atop {5x-2y=2}} \right.$
$\left \{ {{x = y-2} \atop {5x-2y=2}} \right.$
5*(y-2) - 2y = 2
5y - 10 - 2y = 2
3y = 2 + 10
3y = 12
y = 4
$\left \{ {{x=y-2} \atop {y=4}} \right.$
x = 4 - 2
x = 2
$\left \{ {{x=2} \atop {y=4}} \right.$
Ответ: (2;4)