Răspuns:
Explicație pas cu pas:
a)
7·x - 8 = 13
7·x = 13 + 8
7·x = 21
x = 21 : 7
x = 3
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b) 3/4 → 3 supra 4, unde / = linie de fracție
3/4 - 5·x/6 = 1/4
5·x/6 = 3/4 - 1/4
5·x/6 = (2/4)⁽²
5×x/6 = 1/2
x = (1/2) : (5/6)
x = (1/2) × (6/5)
x = 3/5
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c)
(2/5)×x - 1/2 = 1/10
(2/5)× x = 1/10 + ⁵⁾(1/2)
(2/5) · x = 1/10 + 5/10
x = (6/10) : (2/5)
x = (6/10) × (5/2)
x = 3/2
Verific:
(2/5) × (3/2) - 1/2 = ²⁾(3/5) - ⁵⁾(1/2) = 6/10 - 5/10 = 1/10
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d)
1/8 + (1/2) · ( 2x - 1) = 2x - ( 1/8) · ( 8x - 1) - (1/4) · (4x -2)
1/8 + 2x/2 - 1/2 = 2x - 8x/8 + 1/8 - 4x/4 + 2/4
1/8 + x - 1/2 = 2x - x + 1/8 - x + 1/2
x = 1/8 - 1/8 + 1/2 + 1/2
x = 2/2
x = 1
