1. 2 + 3x = -2x - 13
3x + 2x = -13 - 2
3x + 2x = -15
5x = -15
x = -3
2. 2 - 3(2x+2) = 13 - 6x
2 - 6x - 6 = 13 - 6x
-6x + 6x = 13 + 6 - 2
0 = 17 - нет решений
3. 8 - 5(2x - 3) = 13 - 6
8 - 10x + 15 = 7
-10x = 7 - 15 - 8
-10x = - 16
x = 1,6
4. 1 - 2(5-2x) = -x - 3
1 - 10 + 4x = -x - 3
4x + x = -3 + 10 - 1
5x = 6
x = 1,2
5. 5 - 2x = 11 - 7(x+2)
5 - 2x = 11 - 7x - 14
-2x + 7x = 11 - 14 - 5
5x = - 8
x = - 1,6
6. -2(5 - 3x) = 7x + 3
-10 + 6x = 7x + 3
6x - 7x = 3 + 10
- x = 13
x = - 13
7. 3x + 5 + (x + 5) = (1 - x) + 4
4x + 10 = 5 - x
4x + x = 5 - 10
5x = -5
x = - 1
8. 10x + 9 = 7x
10x - 7x = - 9
3x = - 9
x = - 3
9. x - 2 + 3(x - 3) = 3(4 - x) - 3
x - 2 + 3x - 9 = 12 - 3x - 3
4x - 11 = 9 - 3x
4x + 3x = 9 + 11
7x = 20
x = 20/7
1) 3х²-124х-84=0
D = 15376 + 1008 = 16384
√D = 128
x₁ = (124+128)\6 = 42
x₂ = (124 - 128)\6 = -⅔
2) 7х²+6х+1=0
D = 8
√D = 2√2
x₁ = (-3 + √2) \ 7
x₂ = (-3 - √2) \ 7
3)(х²+9х+14)/(х²-49) = (x+2)(x+7) \ (x-7)(x+7) = (x+2) \ (x-7)
х²+9х+14 - приведённое
по т. Виета
x₁ + x₂ = -9
x₁ · x₂ = 14
x₁ = -2
x₂ = -7
Следовательно выражение х²+9х+14 раскладывается на множители (x+2)(x+7)
4) (х^2+4х-21)/(2х^2+11х-21) = (x-3)(x+7) \ (x+7)(2x-3) = (x-3)\(2x-3)
a) х^2+4х-21 = 0
D = 100
√D = 10
x₁=3
x₂= -7
х^2+4х-21 = (x - 3)(x+7)
б) 2х^2+11х-21 = (x+7)(2x-3)
у astragorta во втором уравнении ошибка.
