Đáp án:
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Bài `1`
`[1/2 - (-3/4) + (-1/3)] ÷ 1 5/6`
`= [1/2 + 3/4 - 1/3] ÷ 11/6`
`= [6/12 + 9/12 - 4/12] × 6/11`
`= (6 +9 - 4)/12 × 6/11`
`= 11/12 × 6/11`
`= 1/2`
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Bài `2`
`a,`
`2x - 3 = 5`
`↔ 2x = 5 + 3`
`↔2x = 8`
`↔x=8÷2`
`↔x=4`
Vậy `x=4`
`b,`
`1 5/8 ÷ x - 1 1/4 = 2`
`↔ 13/8 ÷ x - 5/4 = 2`
`↔ 13/8 ÷ x = 2 + 5/4`
`↔ 13/8 ÷ x = 8/4 + 5/4`
`↔ 13/8 ÷ x = 13/4`
`↔ x = 13/8 ÷ 13/4`
`↔ x = 13/8 × 4/13`
`↔ x = 1/2`
Vậy `x=1/2`