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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Tìm x, biết 1). 3/4 – x = 1/5 2). 7/2 + 2x = -3/4 3). -4/3 : x + 3/2 = 5/6 4). -2/3 – 1/3 × ( 2x – 5 ) = 3/2

Toán Lớp 6: Tìm x, biết
1). 3/4 – x = 1/5
2). 7/2 + 2x = -3/4
3). -4/3 : x + 3/2 = 5/6
4). -2/3 – 1/3 × ( 2x – 5 ) = 3/2

Comments ( 2 )

  1. Giải đáp:
    $\\$
    1,
    3/4 -x = 1/5
    ↔ x = 3/4 – 1/5
    ↔x = 15/20 – 4/20
    ↔x = 11/20
    Vậy x=11/20
    $\\$
    2,
    7/2 + 2x = (-3)/4
    ↔ 2x = (-3)/4 – 7/2
    ↔ 2x = (-3)/4 – 14/4
    ↔2x = (-17)/4
    ↔ x = (-17)/4 ÷ 2
    ↔x=(-17)/4 × 1/2
    ↔x=(-17)/8
    Vậy x=(-17)/8
    $\\$
    3,
    (-4)/3 ÷ x + 3/2 = 5/6
    ↔ (-4)/3 ÷ x = 5/6 – 3/2
    ↔ (-4)/3 ÷ x = 5/6 – 9/6
    ↔ (-4)/3 ÷ x = (-2)/3
    ↔x=(-4)/3 ÷ (-2)/3
    ↔x=(-4)/3 × (-3)/2
    ↔x=2
    Vậy x=2
    $\\$
    4,
    (-2)/3 – 1/3 × (2x-5) = 3/2
    ↔ 1/3 × (2x-5) = (-2)/3 – 3/2
    ↔ 1/3 × (2x-5) = (-4)/6 – 9/6
    ↔ 1/3 ×(2x-5)=(-13)/6
    ↔2x-5=(-13)/6 ÷ 1/3
    ↔2x-5=(-13)/6 × 3
    ↔2x-5=(-13)/2
    ↔2x=(-13)/2 + 5
    ↔2x=(-13)/2 + 10/2
    ↔2x = (-3)/2
    ↔x=(-3)/2 ÷ 2
    ↔ x=(-3)/2 × 1/2
    ↔x=(-3)/4
    Vậy x=(-3)/4
     

  2. Hướng dẫn trả lời:
    1) 3/4 – x = 1/5.
    ⇒ x = 3/4 – 1/5.
    ⇒ x = 15/20 – 4/20.
    ⇒ x = 11/20.
    $\text{Vậy x = $\dfrac{11}{20}$.}$
    2) 7/2 + 2x = -3/4.
    ⇒ 2x = -3/4 – 7/2.
    ⇒ 2x = -3/4 – 14/4.
    ⇒ 2x = -17/4.
    ⇒ x=-17/4 ÷ 2.
    ⇒ x=-17/4. 1/2.
    ⇒ x=-17/8.
    $\text{Vậy x = $\dfrac{-17}{8}$.}$
    3) -4/3 ÷ x + 3/2 = 5/6.
    ⇒ -4/3 ÷ x = 5/6 – 3/2.
    ⇒ -4/3 ÷ x = 5/6 – 9/6.
    ⇒ -4/3 ÷ x = – 4/6.
    ⇒ -4/3 ÷ x = – 2/3.
    ⇒ x = (-4/3) ÷ (- 2/3).
    ⇒ x = (-4/3).(- 3/2).
    ⇒ x = 2.
    $\text{Vậy x = 2.}$
    4) -2/3 – 1/3.(2x – 5) = 3/2.
    ⇒ 1/3.(2x – 5) = -2/3 – 3/2.
    ⇒ 1/3.(2x – 5) = -4/6 – 9/6.
    ⇒ 1/3.(2x – 5) = -13/6.
    ⇒ 2x – 5 = -13/6 ÷ 1/3.
    ⇒ 2x – 5 = -13/6. 3/1.
    ⇒ 2x – 5 = -13/2.
    ⇒ 2x = -13/2 + 5.
    ⇒ 2x = -13/2 + 10/2.
    ⇒ 2x = -3/2.
    ⇒ x = -3/2 ÷ 2.
    ⇒ x = -3/2 . 1/2.
    ⇒ x = -3/4.
    $\text{Vậy x = $-\dfrac{3}{4}$.}$

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222-9+11+12:2*14+14 = ? ( )