Question

10) Rezolvaţi în multimea numerelor intregi ecuațiile: 5(2x + 3) = 7x - 21: b) 4(3x - 2) = 8x - 28; 6(15 - x) = 2x + 34; 8 -- 4x = 2(14 + 3x): e) 3(19 - x) = 4x - 13; 6 + 7x = 3(12 + 4x). ©​

Answer 1

Răspuns:

a)

5(2x + 3) = 7x - 21

10x + 15 = 7x - 21

10x - 7x = - 21 - 15

3x = - 36

x = - 36 / 3

x = - 12

b)

4(3x - 2) = 8x - 28

12x - 8 = 8x - 28

12x - 8x = - 28 + 8

2x = - 20

x = - 20/2

x = - 10

c)  

3(19 - x) = 4x - 13

57 - 3x = 4x - 13

57 + 13 = 4x + 3x

70 = 7x

x = 70 : 7

x = 10

d)

6(15 - x) = 2x + 34

90 - 6x = 2x + 34

90 - 34 = 2x + 6x

56 = 8x

x = 56/8

x = 7

e)

8 - 4x = 2(14 + 3x)

8 - 4x = 28 + 6x

- 4x - 6x = 28 - 8

-10x = 20

x = 20/(-10)

x = - 2

f)

6 + 7x = 3(12 + 4x)

6 + 7x = 36 + 12x

7x - 12x = 36 - 6

- 5x = 30

x = 30 /(-5)

x = - 6