№4.
3х + 7 = 9 + х + 2х
3х - х - 2х = - 7 + 9
0х = 2
Уравнение не имеет решения
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№5
4 - 4х + x^2 - х^2 - 1,5x = 4
- 4х - 1,5х = 4 - 4
- 5,5х = 0
х = 0
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№6
7(3х - 5) + 2(8х - 12) = 14 * 9
21х - 35 + 16х - 24 = 126
37х = 126 + 35 + 24
37х = 185
х = 5
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№7
9(3х + 6) - 6(7х - 14) - 2(х + 1) = 0
27х + 54 - 42х + 84 - 2х - 2 = 0
27х - 42х - 2х = - 54 - 84 + 2
- 17х = - 136
х = 8
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№8
х^2 + x + 2x + 2 - (x^2 -3x +4x - 12) = 6
x^2 + 3x + 2 - x^2 +3x - 4x + 12 = 6
2х = - 2 - 12 + 6
2х = - 8
х = - 4
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№9
x^2 - 14x + 49 + 3 = x^2 - 4
x^2 - x^2 - 14x = - 49 - 3 - 4
- 14x = - 56
x = 4
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№10
4x^2 - 12x + 9 - 49 + 28x - 4x^2 = 2
16x = - 9 + 49 + 2
16x = 42
x = 2 целых 5/8