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

Toán Lớp 6: tìm x >_< b) { xEN/30

Toán Lớp 6: tìm x >_< b) { xEN/30

Comments ( 2 )

  1. $b) { x∈N/30<x <40}$
    30<x<40
    ⇒x∈{31;32;33;…..;38;39}
    c)(105 – x ) : 2^5 =3^0 +1
    (105-x):32=1+1
    (105-x):32=2
    105-x=2×32
    105-x=64
    x=105-64
    x=41
    d) 2x -138 =2^2 × 3^2
    2x-138=4×9
    2x-138=36
    2x=138+36
    2x=174
    x=174:2
    x=87
    e)( 6x-39)×28=5628
    6x-39=5628:28
    6x-39=201
    6x=201+39
    6x=240
    x=240:6
    x=40
    f)( 9x +2)×3=60
    9x+2=60:3
    9x+2=20
    9x=20-2
    9x=18
    x=18:2
    x=9
    g)(26-3x):5+71=75
    (26-3x):5=75-71
    (26-3x):5=4
    26-3x=4×5
    26-3x=20
    3x=26-20
    3x=6
    x=6:3
    x=2

  2. b, {x∈N/30<x<40}
    ⇒ x∈{31;32;33;34;35;36;37;38;39}
    c, (105 – x) : 2^5=3^0 + 1
    (105 – x) : 32 = 1 + 1
    (105 – x) : 32 = 2
    105 – x = 2 x 32
    105 – x = 64
              x = 105 – 64
              x = 41.
    d, 2 x x – 138 = 2² x 3² 
    2 x x – 138 = 36
    2 x x = 36 + 138
    2 x x = 174
          x = 174 : 2 
          x = 87.
    e, (6 x x -39) x 28 = 5628
    6 x x -39 = 5628 : 28
    6 x x -39 = 201
    6 x x = 201 + 39
    6 x x = 240
          x = 240 : 6
          x = 40.
    f, (9 x x + 2) x 3 = 60
    9 x x + 2 = 60 : 3
    9 x x + 2 = 20
    9 x x = 20 – 2
    9 x x = 18
          x = 18 : 9
          x = 2.
    g, (26 – 3 x x) : 5 +71 = 75
    (26 – 3 x x) : 5 = 75 – 71
    (26 – 3 x x) : 5 = 4
    26 – 3 x x = 4 x 5
    26 – 3 x x = 20
    3 x x = 26 – 20
    3 x x = 6
          x = 6 : 3
          x = 2.
    Chúc bạn học tốt nha :3
    Cho mình xin ctlhn kèm 5 sao và tim nha :3

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

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