Question

Rozwiąż podane układy równań metodą podstawiania.

a)

{ x+2y=-2

{ 2x-y=1

b)

{ x+4y+ -2

{ 3x-8y+10

c)

{ x-2y=3

{ -2+y=0

d)

{ 2x+y=9

{ 5x-4y=3

e)

{ 3x-2y=5

{ 2x-y=4

f)

{ 2x+9y=-9

{ -3x+ 3y=8

g)

{ 2x+3y=4

{ 8x-5y=-1

h)

{ x-y=0

{ x+y+z=4

{ x+2y+3z=9

Answer 1

a)

{  x+2y=-2

{  2x-y=1

 

{x=-2y-2

{2x-y=1

 

2(-2y-2)-y=1

-4y-4-y-1=0

-5y=5/:(-5)

y=-1

x=-2y-2=-2*-1-2=2-2=0

{y=-1

{x=0

Answer 2

a){x=2y=-2                                              x-2y=-2

{2x-y=1                                                -¼-2y=-2

-2y=¼-2

{x-2y=-2                                               -2y=¼-2/1

{2x-y=1/·(-2)                                        -2y=-½/(-2)

{y=1

{x-2y=-2                                                 {x=-¼

+{-4x+2y=-2

------------------

-3x=-4/:(-3)

x=-¼