Question

Equação do primeiro grau

A) 7(x-2)-2(x+1)=x+5-x
B) 7x-3+2x-2=3x-7+x-4
C) x/4+3x/5=6
D) 3x/2+1/5=x/5+2

Answer 1

a)
7(x - 2) - 2(x + 1) = x + 5 - x
7x - 14 - 2x - 2 = 5
5x - 16 = 5
5x = 5 + 16
5x = 21
x = 21/5

b) 
7x - 3 + 2x - 2 = 3x - 7 + x - 4
9x - 5 = 4x - 11
9x - 4x = - 11 + 5
5x = - 6
x = - 6/5

c)
x + 3x = 6
4     5

5x + 12x = 120
      20         20

5x + 12x = 120

17x = 120
x = 120/17
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Obs.:
mmc: 4,5 = 20

4,5: 2
2,5: 2
1,5: 5
1,1  =  2.2.5 = 4.5 = 20

d)
3x + 1 = x + 2
2      5    5

15x + 2  =  2x + 20  
     10            10

15x + 2 = 2x + 20
15x - 2x = 20 - 2
13x = 18
x = 18/13
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mmc de 2,2,5: 10

2,5,5: 2
1,5,5: 5
1,1,1 =    2.5 = 10