Odpowiedź:
19)
2(3/2 - x ) - 8 = x - 2(x + 2)
3 - 2x - 8 = x - 2x - 4
- 2x - 5 = - x - 4
- 2x + x = - 4 + 5
- x = 1
x = - 1
20)
2 + (4x - 5)/2 = x + 3 | * 2
4 + 4x - 5 = 2x + 6
4x - 2x = 6 + 5 - 4
2x = 7
x = 7/2 = 3 1/2
21)
(2x - 3)(2x + 3) - 4x(x + 2) + 49 = - 4x
4x² - 9 - 4x² - 8x + 49 = - 4x
- 8x + 40 = - 4x
- 8x + 4x = - 40
- 4x = - 40
4x = 40
x = 40/4 = 10
