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

Toán Lớp 7: e.-2 I1/2x – 1/3 I + 3/2 = 1/4 gấp ạ f. 1/2x + 4/5 = 14/24x – 3/2 GẤP

Toán Lớp 7: e.-2 I1/2x – 1/3 I + 3/2 = 1/4 gấp ạ
f. 1/2x + 4/5 = 14/24x – 3/2 GẤP

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    e)
    -2|1/2x-1/3| + 3/2 = 1/4
    \to -2|1/2x-1/3| = 1/4 – 3/2
    \to -2|1/2x-1/3| = -5/4
    \to |1/2x-1/3| = -5/4 : (-2)
    \to |1/2x-1/3| = 5/8
    TH1 : 1/2x – 1/3 = 5/8 \to 1/2x = 23/24 \to x = 23/12
    TH2 : 1/2x – 1/3 = -5/8 \to 1/2x = -7/24 \to x = -7/12
    Vậy x \in {-7/12,23/12}
    f)
    1/2x + 4/5 = 14/24x – 3/2
    \to 30/60x + 48/60 = 35/60x – 90/60
    \to 30x + 48 = 35x – 90
    \to 30x – 35x = -90 – 48
    \to -5x = -138
    \to x = 138/5
    Vậy x \in {138/5}

  2. e) -2 | 1/2x – 1/3| + 3/2 = 1/4
    -2 | 1/2 x – 1/3| = 1/4 – 3/2
    -2 |1/2 x – 1/3| = -5/4
    |1/2x – 1/3| = -5/4 : (-2)
    |1/2 x – 1/3| =  5/8
    ⇒ +) Trường hợp 1 :
    1/2 x – 1/3 = 5/8
    1/2 x = 5/8 + 1/3
    1/2 x = 23/24
    x = 23/24 :  1/2
    x=23/12
    +) Trường hợp 2 :
    1/2x – 1/3 = -5/8
    1/2 x = -5/8 + 1/3
    1/2 x=-7/24
    x = -7/24 : 1/2
    x = -7/12
    Vậy x ∈ { 23/12 ; -7/12}
    f) 1/2x + 4/5 = 14/24x – 3/2
    1/2 x – 14/24x = -3/2 – 4/5
    1/2 x – 7/12 x = -23/10
    ( 1/2 – 7/12)x = -23/10
    -1/12 x = -23/10
    x = -23/10 : (-1/12)
    x= 138/5

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