Question

Exercițiul 1
2x + y=7
x-2y=-4
Exercițiul 2
2x+y=5
-4x-2y=-10
Exercițiul 3
2x-y=3
6x-3y=7

Answer 1

1. $2x+y=7$
$2x=7-y$
$2x:2=7:2-y:2$
$x= \frac{7}{2}- \frac{y}{2}$
$x= \frac{7-y}{2}$, y∈R

$x-2y=-4$
$x=-4+2y$, y∈R

2. $2x+y=5$
$2x=5-y$
$2x:2=5:2-y:2$
$x= \frac{5}{2}- \frac{y}{2}$
$x= \frac{5-y}{2}$, y∈R

$-4x-2y=-10$
$-4x=-10+2y$
$x=-4x:(-4)=-10:(-4)+2y:(-4)$
$x= \frac{10}{4}- \frac{2}{4}y$
$x= \frac{5}{2}- \frac{1}{2}y$, y∈R

3. $2x-y=3$
$2x=3+y$
$2x:2=3:2+y:2$
$x= \frac{3}{2}+ \frac{y}{2}$
$x= \frac{3+y}{2}$, y∈R

$6x-3y=7$
$6x=7+3y$
$6x:6=7:6+3y:6$
$x= \frac{7}{6}+ \frac{3}{6}y$
$x= \frac{7}{6}+ \frac{1}{2}y$, y∈R