Question

Решить систему уравнений методами подстановки

4x-y=5
x+3y=-2

Answer 1

4x - y = 5
x + 3y = -2

4x - y = 5
x = -2 - 3y

4(-2 - 3y) - y = 5
-8 - 12y - y = 5
-13y = 13
y = -1

x = -2 - 3 * (-1) = -2 + 3 = 1

Ответ: (1;-1)

Answer 2

$\left \{ {{4x-y=5} \atop {x+3y=-2}} \right. \\\\ \left \{ {{y=4x-5} \atop {x+3(4x-5)=-2}} \right.\\\\ \left \{ {{y=4x-5} \atop {x+12x-15=-2}} \right. \\\\ \left \{ {{y=4x-5} \atop {13x=13}} \right. \\\\ \left \{ {{x=1} \atop {y=4*1-5}} \right.\\\\ \left \{ {{x=1} \atop {y=-1}} \right.$
Ответ: (1 ; - 1)