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

Toán Lớp 6: Bài 1: Tìm x, biết. a) x + 30 = – 4 b) (2x – 5) + 17 = 6 c)324 –

Toán Lớp 6: Bài 1: Tìm x, biết.
a) x + 30 = – 4 b) (2x – 5) + 17 = 6
c)324 – ( 318 – x ) = 115 d)( – 300 ): 20 + 5. ( 3x – 1) = 25

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết :
    a) x + 30 = – 4
    ⇔ x = – 4 – 30
    ⇔ x = – ( 4 + 30 )
    ⇔ x = – 34
    Vậy x = – 34
    b) ( 2x – 5 ) + 17 = 6
    ⇔ 2x – 5 + 17 = 6
    ⇔ 2x + 12 = 6
    ⇔ 2x = 6 – 12
    ⇔ 2x = – 6
    ⇔ x = – 6 : 2
    ⇔ x = – 3
    Vậy x = – 3
    c) 324 – ( 318 – x ) = 115
    ⇔ 324 – 318 + x = 115
    ⇔ 6 + x = 115
    ⇔ x = 115 – 6
    ⇔ x = 109
    Vậy x = 109
    d) ( – 300 ) : 20 + 5 ( 3x – 1 ) = 25
    ⇔ – 15 + 15x – 5 = 25
    ⇔ 15x – 20 = 25
    ⇔ 15x = 25 + 20
    ⇔ 15x = 45
    ⇔ x = 45 : 15
    ⇔ x = 3
    Vậy x = 3

  2. a) x + 30 = – 4
    <=>x=-4-30
    <=>x=-34
    Vậy x=-34
    b)
    (2x – 5) + 17 = 6
    <=>2x-5=6-17
    <=>2x-5=-11
    <=>2x=-6
    <=>x=-3
    Vậy x=-3
    c)
    324 – ( 318 – x ) = 115
     <=>318-x=324-115
    <=>318-x=209
    <=>x=109
    Vậy x=109
    d)
    ( – 300 ): 20 + 5. ( 3x – 1) = 25
    <=>-15+5(3x-1)=25
    <=>-15+15x-5=25
    <=>15x-20=25
    <=>15x=45
    <=>x=3
    Vậy x=3
     

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