1.Tìm x, biết:
a) 7/8 + x = 4/7
⇔ x = 4/7 - 7/8
⇔ x = -17/56
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b) 6 – x = (-3)/4
⇔ x = 6 - (-3)/4
⇔ x = 27/4
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c) 1/(-5) + x = 3/4
⇔ x = 3/4 + 1/5
⇔ x = 19/20
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d) –6 – x = (-3)/5
⇔ -x = (-3)/5 +6
⇔ -x = 27/5
⇔ x = -27/5
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e) - 2/6 + x = 5/7
⇔ x = 5/7 + 2/6
⇔ x = 22/21
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f) -8 – x = (-5)/3
⇔ -x = -5/3 +8
⇔ x = -19/3
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g) - 2/10 – x = - 9/8
⇔ -x = -9/8 + 2/10
⇔ x = 37/40
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h) 8 – x = (-1)/6
⇔ x = 8 - (-1)/6
⇔ x = 49/6
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i) - 2/5 + x = 5/7
⇔ x = 5/7 + 2/5
⇔ x = 39/35
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j) -2 – x = (-5)/3
⇔ -x = (-5)/3 +2
⇔ x = -1/3
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k) - 1/6 – x = - 9/8
⇔ -x = -9/8 +1/6
⇔ x = 23/24
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l) 8 – x = (-1)/5
⇔ x = 8 - (-1)/5
⇔ x = 41/5