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

Toán Lớp 7: a, x + 1/6 = -3/8 b, 1/2 x + 1/8 x = 3/4 c, 2- / 3/4 – x/ = 7/12 d, ( 2x – 4,5) : 3/4 – 1/3 =1

Toán Lớp 7: a, x + 1/6 = -3/8
b, 1/2 x + 1/8 x = 3/4
c, 2- / 3/4 – x/ = 7/12
d, ( 2x – 4,5) : 3/4 – 1/3 =1

Comments ( 2 )

  1. Giải đáp:
     ↓↓↓
    Lời giải và giải thích chi tiết:
    a) x+1/6=-3/8
          x      =-3/8-1/6 
          x      =-13/24
    b) 1/2x + 1/8x = 3/4
           x. ( 1/2+1/8)=3/4
           x. 5/8         =3/4
           x                =3/4:5/8
           x                =6/5
    c) 2-|3/4-x|=7/12
              |3/4-x|=2-7/12
              |3/4-x|=17/12
    3/4-x=17/12          hoặc   3/4-x=-17/12
           x=3/4-17/12                   x=3/4-(-17/12)
           x=-2/3                             x=13/6
                 Vậy x∈{-2/3;13/6}
    d) (2x-4,5):3/4-1/3=1
          (2x-4,5):3/4     =1+1/3
          (2x-4,5):3/4     =4/3
          2x-4,5              =4/3 . 3/4
          2x-4,5              =1
          2x                    =1+4,5
          2x                    =5,5
            x                    =5,5:2
            x                    =11/4

  2. a) x + 1/6 = -3/8
    x = -3/8 – 1/6
    x = -13/24
    Vậy x = -13/24
    b) 1/2 x + 1/8 x = 3/4
    ( 1/2 + 1/8) x = 3/4
    5/8 . x = 3/4
    x = 3/4 : 5/8
    x = 6/5
    Vậy x = 6/5
    c) 2 – | 3/4 – x | = 7/12
    |3/4 – x| = 2 – 7/12
    |3/4 – x| = 17/12
    ⇒ +) 3/4 – x = 17/12
    x = 3/4 – 17/12
    x= -2/3
    +) 3/4 – x = -17/12
    x = 3/4 – (-17/12)
    x= 13/6
    Vậy x∈ { -2/3 ; 13/6}
    d) ( 2x – 4,5) : 3/4 – 1/3 = 1
    ( 2x – 9/2) : 3/4 = 1 + 1/3
    ( 2x – 9/2) : 3/4= 4/3
    (2x – 9/2)= 4/3 * 3/4
    2x – 9/2 = 1
    2x = 1 + 9/2
    2x = 11/2
    x = 11/2 : 2
    x= 11/4
    Vậy x = 11/4

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

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