Răspuns:
Explicație pas cu pas:
1)
a) 2x – 5 = 7x + 25
2x - 5 - 25 = 7x
2x - 30 = 7x
- 30 = 7x - 2x
5x = -30 |:5
x = -6
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b) 4x – 3 = 8x + 9
4x - 3 - 9 = 8x
4x - 12 = 8x
- 12 = 8x - 4x
4x = - 12 |:4
x = -3
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c) 3x – 1 = 5x + 7
3x - 1 - 7= 5x
3x - 8 = 5x
- 8 = 5x - 3x
2x = -8 |:2
x = -4
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d) identic ca punctul a)
2)
a) 3x – 2∙(4x – 1) = 12
3x - 8x + 2 = 12
-5x = 10 |:(-5)
x = -2
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b) 5 – 3∙(2x – 5) = 4x
5 - 6x + 15 = 4x
20 - 6x = 4x
20 = 4x + 6x
20 = 10x
x = 2
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c) 2x – 3∙(4x – 1) = 13
2x - 12x + 3 = 13
-10x + 3 = 13
-10x = 13 - 3
-10x = 10
x = -1
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d) 7 - 2∙(4x - 3) = 5x
7 - 8x + 6 = 5x
13 - 8x = 5x
13 = 5x + 8x
13 = 13x
x = 1
3)
a) 4∙(5x – 2) + 3=2∙(10x – 1)
20x - 8 + 3 = 20x - 2
20x - 5 = 20x - 2
-5 = - 2 (fals) posibil ai scris gresit enuntul
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b) 3∙(2x – 3) + 1=2∙(3x – 4)
6x - 9 + 1 = 6x - 8
6x - 8 = 6x - 8
6x - 6x = -8 + 8
0 = 0 (adevarat)
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c) 2∙(3x + 5) - 4 = 6∙(x + 1)
6x + 10 - 4 = 6x + 6
6x + 6 = 6x + 6
6x - 6x = 6 - 6
0 = 0 (adevarat)
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d) 3∙(4x – 3) + 5=6∙(2x – 1)
12x - 9 + 5 = 12x - 6
12x - 4 = 12x - 6
- 4 = - 6 (fals)
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