x + 4y = - 12
4y = - 12 - x
y = ( - 12 - x ) : 4
y = - 3 - 0,25x
****************
x = 4
y = - 3 - 1 = - 4
( 4 ; - 4 )
****************
х = - 8
y = - 3 + 2 = - 1
( - 8 ; - 1 )
-----------------------------------------------
x - 3y = 6
3y = x - 6
y = 1/3( x - 6 )
y = 1/3x - 2
*************
x = 3
y = 1 - 2 = - 2
( 3 ; - 2 )
***************
x = - 3
y = - 1 - 2 = - 3
( - 3 ; - 3 )
--------------------
- x + 2y = 5
2y = x + 5
y = ( x + 5 ) : 2
y = 0,5x + 2,5
******************
x = 1
y = 0,5 + 2,5 = 3
( 1 ; 3 )
********************
x = - 1
y = - 0,5 + 2,5 = 2
( - 1 ; 2 )