Question

Calcule:

4.(x+3)=20

5.(2x-1)=2.(x+4)

10-2(x+3)=8+3.(2x+5)

3x - 1 = x - 2
5     2        5

x + 3 = 2x -1
2    4     6   3

3y - 1 = 3 - 2y
2           4

Answer 1

a) 4 (x + 3) = 20
4x + 12 = 20
4x = 20 - 12
4x = 8
x = 8/4
x = 2

b) 5 (2x - 1) = 2 (x + 4)
10x - 5 = 2x + 8
10x - 2x = 8 + 5
8x = 13
x = 13/8

c) 10 - 2 (x + 3) = 8 + 3 (2x + 5 )
10 - 2x - 6 = 8 + 6x + 15
- 2x - 6x = 15 + 8 + 6 - 10
- 8x = 19  (-1)
8x = - 19
x = - 19/8

d) 3x - 1 = x - 2
    5    2      5
tira mmc entre 2 e 5 = 10

6x - 5 = 2 ( x - 2 )
          10
corta o 10

6x - 5 = 2 (x - 2)
6x - 5 = 2x - 4
6x - 2x = - 4 + 5
4x = 1
x = 1/4

e) x + 3 = 2x - 1
   2    4    6     3

tira mmc entre 2,3, 4 e 6 = 12

6x + 9 = 4x - 4
       12
6x - 4x = - 4 - 9
2x = - 13
x = - 13/2

f)  3y - 1 = 3 - 2y
    2         4

tira mmc  entre 2 e 4 = 8

12y - 8 = 6 - 16y
          8
12y - 8 = 6 - 16y
12y + 16y = 6 + 8
28y = 14
y = 14/28
y = 1/2