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

Toán Lớp 6: B1: Tìm X: a, 17-(2+X)=3 b, (6+X)-(17-21)=-25 c, -10-(31-X)=40 B2:Tính nhanh: a, 321+{ -15+[30+(-321)] } b. (2016+432)+[ 168+(-2016)]

Toán Lớp 6: B1: Tìm X:
a, 17-(2+X)=3
b, (6+X)-(17-21)=-25
c, -10-(31-X)=40
B2:Tính nhanh:
a, 321+{ -15+[30+(-321)] }
b. (2016+432)+[ 168+(-2016)]

Comments ( 2 )

  1. 1
    a. 17-(2+x)=3
    <->17-2-x=3
    <->x=17-2-3=12
     b. (6+x)-(17-21)=3
    <->6+x-17+21=-25
    <->x=-6+17-21-25=-35
     c. -10-(31-x)=40
    <->-10-31+x=40
    <->x=40+10+31=81
    2
    a 321+{ -15+[30+(-321)] }
    =321+-15+30+-321
    =(321+-321)+15
    =0+15
    =15
    b(2016+432)+[ 168+(-2016)]
    =2160+432+168+-2016
    =(2160+-2160)+(432+168)
    =0+600
    =600

  2. $\\$
    Bài 1.
    a,
    17 – (2+x)=3
    ->2+x=17-3
    ->2+x=14
    ->x=14-2
    ->x=12
    Vậy x=12
    b,
    (6+x) – (17 – 21)=-25
    ->(6+x)-(-4)=-25
    -> 6+x=-25 + (-4)
    -> 6+x=-29
    ->x=-29-6
    ->x=-35
    Vậy x=-35
    c,
    -10 – (31-x)=40
    -> 31-x=-10-40
    ->31-x=-50
    ->x=31-(-50)
    ->x=81
    Vậy x=81
    $\\$
    Bài 2.
    a,
    321 + {-15 + [30 + (-321)]}
    = 321+ {-15 + 30 – 321}
    = 321 -15 + 30-321
    = (321 – 321) + (-15+30)
    =0+15
    = 15
    b,
    (2016 + 432) + [168 + (-2016)]
    = 2016 + 432 + 168 – 2016
    = (2016 -2016) + (432 + 168)
    = 0 + 600
    = 600

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