Question

Zadanie 6 strona 71 . Rozwiąż równania.

c.) x/7 = 4/5

d.) 5x -3 / 9 = 3x +7 / 5

e.) 3(x-1) / 3 = -x-7 / 5

f.) x-3 / 8 = x+3 /12

g.) 4+8x / 2 = 3(x+13) / 7

h.) 5(x-2) /3 = 5x - 20 /4

i.) 4-x /3 = x+6 / 2

j.) 3(x-2) /5 = 4(x+3) / 3

Answer 1

c)

x/7  = 4/5

5x = 28   /:5

x = 5,6

 

d)

5x-3/9 = 3x+7/5

5(5x+3) = 9 (3x+7)

25x + 15 = 27x + 63

25x – 27x = 63 – 15

-2x = 48   / : (-2)

x = -12

 

e)

3(x-1)/3 =  -x-7/5

5*3(x-1) = 3 (-x-7)

15x – 15 = - 3x – 21

15x + 3x = -21 + 15

18x = -6    /: 18

x = -6/18

x = - 1/3

 

f)

x-3/8 = x+3/12

12(x-3) = 8(x+3)

12x – 36 = 8x + 24

12x – 8x = 24 + 36

4x = 60   /:4

x = 15

 

g)

4+8x/2 = 3(x+13)/7

7(4+8x) = 2*3(x+13)

28 + 56x = 6x + 78

56x – 6x = 78 – 28

50x = 50    /:50

x = 1

 

h)

5(x-2)/3 = 5x-20/4

4*5(x-2) = 3(5x-20)

20x – 40 = 15x – 60

20x – 15x = -60 – 40

5x = - 100   /:5

x = -20

 

i)

4-x/3 = x+6/2

2(4-x) = 3 (x+6)

8 – 2x = 3x + 18

-2x – 3x = 18 – 8

-5x = 10  /: (-5)

x = -2

 

j)

3(x-2)/5 = 4(x+3)/3

3*3(x-2) = 5*4(x+3)

9x – 18 = 20x + 60

9x – 20x = 60+18

-11x = 78   /: (-11)

x = - 78/11

x = - 7 i 1/11