Odpowiedź :
a) {x+2y=9
{y-1=3x
{x+2y=9
{-3x+y=1 /*(-2)
{x+2y=9
+ {6x-2y= -2
7x=7 /7
x=1
y-1=3x
y=3*1+1
y=3+1
y=4
x=1
y=4
c){-x-y=2
{ 2 (3x+y)=-20
{-x-y=2 /*2
{6x+2y=-20
{-2x-2y=4
+ {6x+2y=-20
4x = -16 /4
x = -4
-x-y=2
-4-y=2
-y = 2+4
-y = 6 /-1
y =- 6
x= -4
y = -6
{y-1=3x
{x+2y=9
{-3x+y=1 /*(-2)
{x+2y=9
+ {6x-2y= -2
7x=7 /7
x=1
y-1=3x
y=3*1+1
y=3+1
y=4
x=1
y=4
c){-x-y=2
{ 2 (3x+y)=-20
{-x-y=2 /*2
{6x+2y=-20
{-2x-2y=4
+ {6x+2y=-20
4x = -16 /4
x = -4
-x-y=2
-4-y=2
-y = 2+4
-y = 6 /-1
y =- 6
x= -4
y = -6
{x+2y=9
{y-1=3x
{x+2y=9
{-3x+y=1 /*(-2)
{x+2y=9
+ {6x-2y= -2
7x=7 /7
x=1
y-1=3x
y=3*1+1
y=3+1
y=4
x=1
y=4
{y-1=3x
{x+2y=9
{-3x+y=1 /*(-2)
{x+2y=9
+ {6x-2y= -2
7x=7 /7
x=1
y-1=3x
y=3*1+1
y=3+1
y=4
x=1
y=4