Question

Решите систему уравнений:
{х+8у= -6,
5х- 2у = 12.

Answer 1

$\left \{ {{x+8y=-6} \atop {5x-2y=12}|*4} \right. \left \{ {{x+8y=-6} \atop {20x-8y=48}} \right. \\ 21x=42 \\ x=42/21=2 \\ x+8y=-6 \\ 8y=-6-x \\ y= \frac{-6-x}{8} = \frac{-6-2}{8} =-1$
отв:(2;-1)

Answer 2

x+8y=-6⇒x=-6-8y
5x-2y=12
5(-6-8y)-2y=12
-30-40y-2y=12
-42y=42
y=-1
x=-6+8
x=2
(2;-1)