Question

Proszę nie muszą być wszystkie zadania .

Answer 1

Zad.1

a)

2(x+y) – (x-y) = 4         

3 (x – 2y) + 4 (x+y) = 5      

 

2x + 2y –x + y = 4

3x – 6y + 4x + 4y = 5

 

x  + 3y = 4    /*(-7)

7x  - 2y = 5

 

-7x – 21y = -28

7x – 2y = 5

-------------------  

-23y  = - 23    /: (-23)

y = 1

 

2 (x+1) – (x-1) = 4

2x + 2 – x +1 = 4

x = 4 -3

 

x = 1

y = 1

 

b)

4(x+2y) – 3(x-y) = 42       

2(y-x) + 3(x-y) = -6           

 

4x + 8y – 3x + 3y = 42

2y – 2x + 3x – 3y = -6

 

x + 11y = 42

x – y = -6     /* (-1)

 

x + 11y = 42

-x + y = 6

----------------  

12y = 48    /: 12

y = 4

 

4(x + 2*4) – 3(x-4) = 42

4(x+8) – 3x + 12 = 42

4x + 32 – 3x + 12 = 42

x = 42 – 44

 

x = - 2

y = 4

 

c)

3(x+y) – 2(x-2y) = 5

2(x+2) – 4(y+1) = -8

 

3x + 3y  - 2x + 4y = 5

2x + 4 – 4y -4 = -8

 

x + 7y = 5     /* (-2)

2x – 4y = -8

 

-2x – 14y = -10

2x – 4y = -8

----------------- 

-18y = -18    / : (-18)

y = 1

 

3(x+1) – 2(x-2*1) = 5    

3x + 3 – 2x + 4 = 5

x = 5-7

 

x = -2

y = 1

 

d)

2(3x+4y) – 7(y-x) = -37       

4(x+2) – (y-4) = -2          

 

6x + 8y – 7y + 7x = -37

4x + 8 –y + 4 = -2

 

13x + y = -37

4x – y =  -14

---------------------  

17x = -51    /:17

x = -3

 

2 [3*(-3) +4y] – 7 ( y +3) = -37

-18 + 8y – 7y -21 = -37

y = -37 + 39

 

y= 2

x= -3                                    

 

zad.2

a)

2/3x + 1/2y = 5    /*6

1/3x – 1/3y = -1    /*3

 

4x + 3y = 30

x – y = -3     /*3

 

4x + 3y = 30

3x –3 y = -9

--------------- 

7x = 21    /:7

x = 3

1/3 *3 – 1/3y = -1

 1-1/3y = -1

-1/3y = -1-1

-1/3y = -2    /*(-3)

 

y = 6

x= 3

 

b)

1/4x + 1/6y = 2    /*12

1/2x – 1/3 y = 0     /*6

 

3x + 2y = 24

3x – 2 y = 0

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

6x = 24  /:6

x = 4

 

¼ * 4 + 1/6y = 2

1 + 1/6y = 2

1/6y = 2 – 1

1/6y = 1    /*6

 

y = 6

x= 4

 

c)

1/3x + 1/5y = 0    /*15

2/3x – 4/5y = -6    / 15

 

5x + 3y = 0

10x – 12y = -90    /: (-2)

 

5x + 3y = 0

-5x + 6y = 45

----------------- 

9y = 45    /:9

y = 5

 

1/3x  + 1/5 *5 = 0

1/3x + 1 = 0

1/3x = -1    /*3

 

x = -3

y = 5

 

d)

1/3x + 2/5y = 4      /*15

1/2x – 1/10y = -1      /*10

 

 

5x + 6y = 60

5x – y = -10   / *(-1)

 

5x +6y = 60

-5x + y = 10

---------------- 

7y = 70   /:7

y = 10

 

1/3x + 2/5*10 = 4

1/3x + 4 = 4  

1/3x = 4 – 4

1/3x =  0     /*3

 

x =  0

y = 1