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Ответы
4.2)
a^2 = b^2
В таком случае два варианта:
a = b или a = -b *можно доказать через модуль
А) 1) 3x - 5 = 4x + 1
-5 - 1 = 4x - 3x
-6 = x
x = -6
2) 3x - 5 = -(4x + 1)
3x - 5 = -4x - 1
3x + 4x = -1 + 5
7x = 4
x = 4/7
Б) 1) 6x - 11 = 19x - 77
-11 + 77 = 19x - 6x
66 = 13x
x = 66/13
2) 6x - 11 = -(19x - 77)
6x - 11 = -19x + 77
6x + 19x = 77 - 11
25x = 66
x = 2,64
В) 1) 54x - 57 = 14x - 67
54x - 14x = -67 + 57
40x = -10
x = -4
2) 54x - 57 = -(14x - 67)
54x - 57 = -14x + 67
54x + 14x = 67 + 57
68x = 124
x = 31/17
Г) 1) 13x - 19 = 19x - 13
-19 + 13 = 19x + 13x
-6 = 32x
x = -0.1875
2) 13x - 19 = -(19x - 13)
13x - 19 = -19x + 13
13x + 19x = 13 + 19
30x = 32
x = 16/15
4.3) Произведение равно нулю в том случае, если один из множителей равен нулю
ab = 0
a = 0 | b = 0
А) 3x + 4 = 0
3x = -4
x = -4/3
5x + 1 = 0
5x = -1
x = -0,2
Б) -5x - 15 = 0
-5x = 15
x = -3
x - 7 = 0
x = 7
В) -9x - 8 = 0
-9x = 8
x = -8/9
-x - 7 = 0
x = -7
Г) 3 - 9x = 0
9x = 3
x = 3
x - 5 = 0
x = 5