Question

Реши систему уравнений:
{2x−y=8
{x−3y=7
{x=
{y=

Answer 1

Ответ:

$\left \{ {{2x-y=8} \atop {x-3y=7}} \right.$

$\left \{ {{y=-8+2x} \atop {x-3y=7}} \right.$

$\left \{ {{y=-8+2x} \atop {x-3*(-8+2x)=7}} \right.$

$\left \{ {{y=-8+2x} \atop {x+24-6x=7}} \right.$

$\left \{ {{{y=-8+2x} \atop {-5x=-17}} \right.$

$\left \{ {{y=-8+2x \atop {x=3.4} \right.$

$\left \{ {{y=-8+2*3.4} \atop {x=3.4}} \right.$

$\left \{ {{y=-1.2} \atop {x=3.4}} \right.$

Проверяем :

$\left \{ {{2*3.4-(-1.2)=8} \atop {3.4-3*(-1.2)=7}} \right.$