Question

PILNE NA JUTRO !!!

a ){ 3x+y = 13

{ 2x-y = 7

b) { 2x-4y = 2

{ x+y = 4

c) { x+3y = 0

{ y-x = 4

d) { x+4 = -4

{ 2x-3y = 2

e) { x-5y = -2

{ 2x+y = -4

f) {2x+y = 3

{x-y = 9

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Answer 1

a ){ 3x+y = 13

{ 2x-y = 7

3x+y+2x-y=20

5x=20/:5

x=4

3x+y = 13

3*4+y=13

12+y=13

y=1

b) { 2x-4y = 2

{ x+y = 4/*4

2x-4y=2

4x+4y=16

2x-4y+4x+4y=18

6x=18/:6

x=3

2x-4y=2

2*3-4y=2

6-4y=2

-4y=-4/:(-4)

y=1

c) { x+3y = 0

{ y-x = 4

x+3y+y-x=4

4y=4/:4

y=1

y-x = 4

1-x=4

-x=3/:(-1)

x=-3

d) { x+4= -4

{ 2x-3y = 2

x=-8

2*(-8)-3y=2

-16-3y=2

-3y=18/:(-3)

y=-6

e) { x-5y = -2/*(-2)

{ 2x+y = -4

-2x+10y=4

2x-y=-4

-2x+10y+2x-y=0

9y=0/:9

y=0

2x-y=-4

2x-0=-4

2x=-4/:2

x=-2

f)  {2x+y = 3

{x-y = 9

2x+y+x-y=12

3x=12/:3

x=4

x-y=9

4-y=9

-y=5/:(-1)

y=-5

 

liczę na naj ;d

 

Answer 2

a)

{3x+y=13 / *2

{2x-y=7 / *(-3)

 

  {6x + 2y=26

+ {-6x+3y=-21

 

5y=5 / /5

y=1

 

3x+1=13

3x=12 / /3

x=4

 

{x=4

{y=1

 

b)

{2x-4y=2

{x+y=4 / *(-2)

 

  {2x-4y=2

+ {-2x-2y=-8

 

-6y=-6 / /(-6)

y=1

 

x+1=4

x=3

 

{x=3

{y=1

 

c)

  {x+3y=0

+ {y-x=4

 

4y=4 / /4

y=1

 

x+3*1=0

x+3=0

 

{x=-3

{y=1

 

d)

{x+4=-4

{2x-3y=2

 

{x=0

{2*0-3y=2

 

{x=0

{-3y=2 / /(-3)

 

{x=0

{y=-1,5

 

e)

{x-5y=-2 / *(-2)

{2x+y=-4

 

  {-2x+10y=4

+ {2x+y=-4

 

11y=0 / /11

y=0

 

x-5*0=-2

x-0=-2

x=-2

 

{x=-2

{y=0

 

f)

{2x+y=3

{x-y=9 / *(-2)

 

  {2x+y=3

+ {-2x+2y=-18

 

3y=-15 / /3

y=-5

 

2x-5=3

2x=8 / /2

x=4

 

{x=4

{y=-5