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

Toán Lớp 6: Tìm số nguyên x, biết: a) x – 7 = 12 + 2 b) 12.x – 44 = – 8 c) 3.(x+5) mũ 3 = 81

Toán Lớp 6: Tìm số nguyên x, biết:
a) x – 7 = 12 + 2
b) 12.x – 44 = – 8
c) 3.(x+5) mũ 3 = 81

Comments ( 2 )

  1. a) x – 7 = 12 + 2
    ⇔ x – 7 = 14
    ⇔ x = 14 + 7
    ⇔ x = 21
    Vậy x = 21
    b) 12 . x – 44 = – 8
    ⇔ 12x = – 8 + 44
    ⇔ 12x = 36
    ⇔ x = 36 : 12
    ⇔ x = 3
    Vậy x = 3
    c) 3 ( x + 5 )^3 = 81
    ⇔ ( x + 5 )^3 = 81 : 3
    ⇔ ( x + 5 )^3 = 27
    ⇔ ( x + 5 )^3 = 3^3
    ⇔ x + 5 = 3
    ⇔ x = 3 – 5
    ⇔ x = – 2
    Vậy x = – 2

  2. a)x-7=12+2
      x-7=14
      x=14+7
      x=21
    b) 12.x – 44 = – 8
            12x  =-8+44
            12x  =36
              x  =36:12
              x   =3
    c) 3.(x+5) mũ 3 = 81
          (x+5)^3=81:3
          (x+5)^3=27
          (x+5)^3=3^3
          x+5=3
          x  =3-5
         x    = -2

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