1)
{-3x + y = -30
+ {3x + 2y = 21
----------------------
3y = -9 | : 3
y = -3
-3x - 3 = -30
-3x = -30 + 3
-3x = -27 | : (-3)
x = 9
2)
{13x - 12y = 14
{7x - 4y = 10 | * (-3)
{13x - 12y = 14
+ {-21x + 12y = -30
----------------------------
-8x = -16 | : (-8)
x = 2
7 * 2 - 4y = 10
14 - 4y = 10
-4y = 10 - 14
-4y = -4 | : (-4)
y = 1
3)
{2x - 4y = 1 | * 5
{5x - 10y = 2,5 * (-2)
{10x - 20y = 5
+ {-10x + 20y = -5
--------------------------
0 = 0
Każda para liczb spełnia podany układ równań
