Объяснение:

1) 3x + 6 = 2(2x - 7) - x

3x + 6 = 4x - 14 - x

3x + 6 = 3x - 14

6 = -14

x є ∅

2) 6,2(3 - 2x) = 20 - (12,4x - 1,4)

18,6 - 12,4x = 20 - 12,4x + 1,4

18,6 = 20 - 1,4

18,6 = 18,6

x є R

3) 2/3(1/3x-1/2) = 4x + 2 1/2

2/9 x - 1/3 = 4x + 2 1/2

0 = 4x - 2/9x + 2 1/2 + 1/3

3 7/9x + 5/2 + 1/3 = 0

3 7/9x + 17/6 = 0

34/9x = - 17/6

x = - 17/6 * 9/34 x

x = - 3/4