Question

1. [x + 2y = 5 [ x- y = -1 2. [x + 3y = 8 [ 2x +y =11 3. [2x+ y = -4 [x - y = - 2 4. [5x - 2y= 4 [x + y = 5 5. [2x + 4y = 5y -1 [y + 5 = 0 6. [x + 2y = 4 [-4x +y=2 7. [x- 3 = 0 [3y - 6x= 12 8. [y- 4 = 0 [3x - y =8 9. [y - 4= 0 [3x -y= 8 10. [x = 4 -3y [x + y = -6 11. [x -3y = -4 [5x - 2y= -7 12. [-2x + y = -8 [ 4x - 3y = 2 13. [-3x - 2y = -2 [2x + 3y = -2 14. [x + 7y= 22 [y = 5x -2 15. [ y = 2x - 8 [-12x + 9y = -6 16. [x + y = 3 [ x - 2y = 6 17. [ 2x - 3y = -5 [ -x + 5y = 6

Macie obok siebie ale to jest jeden na drugim w kazdym przykladzie wiecie o co chodzi z gory thx ; )

Answer 1

 

1) [x + 2y = 5

     [ x- y = -1 /*2

 

[x+2y=5

[2x-2y=-2  +

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

3x=3/:3

x=1

 

 1+2y=5

2y=-1+5

2y=4/:2

y=2

 

2) [x + 3y = 8

     [ 2x +y =11/*(-3)

 

[x+3y=8

[-6x-3y=-33 +

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

-5x=-25/:(-5)

x=5

5+3y=8

3y=-5+8

3y=3/:3

y=1

 

3) [2x+ y = -4

     [x - y = - 2  +

     -----------------

     3x=-6/:3

x= -2

-4+y=-4

y=4-4

y=0

 

4) [5x - 2y= 4

     [x + y = 5/*2

 

[5x-2y=4

[2x+2y=10  +

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

7x=14/:7

x=2

10-2y=4

-2y=-10+4

-2y=-6/:(-2)

y=3

 

6) [x + 2y = 4

    [-4x +y=2/*(-2)

 

[x+2y=4

[8x-2y=-4  +

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

9x=0/:9

x=0

2y=4/:2

y=2

 

10) [x = 4 -3y

       [x + y = -6

 

[x+3y=4

[x+y=-6/*(-3)

 

[x+3y=4

[-3x-3y=18  +

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

-2x=22/:(-2)

x=-11

-11+3y=4

3y=11+4

3y=15/:3

y=5

 

11) [x -3y = -4/*2

       [5x - 2y= -7/*(-3)

 

[2x-6y=-8

[-15x+6y=21  +

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

-13x=-13/:(-13)

x=1

2-6y=-8

-6y=-2-8

-6y=-10/:(-6)

y=5/3

 

12) [-2x + y = -8/*3

       [ 4x - 3y = 2

 

[-6x+3y=-24

[4x-3y=2    +

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

-2x=-22/:(-2)

x=11

44-3y=2

-3y=-44+2

-3y=-42/:(-3)

y=14

 

13) [-3x - 2y = -2/*3

       [2x + 3y = -2/*2

 

[-9x-6y=-6

[4x+6y=-4   +

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

-5x=-10/:(-5)

x=2

8+6y=-4

6y=-8-4

6y=-12/:6

y=-2

 

14) [x + 7y= 22

       [y = 5x -2

 

[x+7y=22

[-5x+y=-2/*(-7)

 

[x+7y=22

[35x-7y=14  +

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

36x=36/:36

x=1

1+7y=22

7y=-1+22

7y=21/:7

y=3

 

15) [ y = 2x - 8

       [-12x + 9y = -6

 

[-2x+y=-8/*(-9)

[-12x+9y=-6

 

[18x-9y=72

[-12x+9y=-6  +

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

   6x=66/:6

x=11

-132+9y=-6

9y=132-6

9y=126/:9

y=14

 

16) [x + y = 3/*2

       [ x - 2y = 6

 

[2x+2y=6

[x-2y=6   +

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

3x=12/:3

x=4

4-2y=6

-2y=-4+6

-2y=2/:(-2)

y=-1

 

17) [ 2x - 3y = -5/*5

       [ -x + 5y = 6 /*3

 

[10x-15y=-25

[-3x+15y= 18  +

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

7x=7/:7

x=1

10-15y=-25

-15y=-10-25

-15y=-35/:(-15)

y=7/3