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

Toán Lớp 7: tính nhanh 1. 2/3 + 4/9 + 1/5 + 2/15 +3/2 – 17/18 2. 13/28 x 5/12 – 5/28 x 1/12 3. 19/4 x 15/23 – 15/4 x 7/23 + 15/4 x 11/23

Toán Lớp 7: tính nhanh
1. 2/3 + 4/9 + 1/5 + 2/15 +3/2 – 17/18
2. 13/28 x 5/12 – 5/28 x 1/12
3. 19/4 x 15/23 – 15/4 x 7/23 + 15/4 x 11/23

Comments ( 1 )

  1. Giải đáp:
     1. 2
    2. 2/21
    3. 15/4
    Lời giải và giải thích chi tiết:
     1.
    2/3 + 4/9 + 1/5 + 2/15 +3/2 – 17/18
    = (2/3 + 1/5 + 2/15) + (4/9 + 3/2 – 17/18)
    = (10/15 + 3/15 + 2/15) + (8/18 + 27/18 – 17/18)
    = 15/15 + 18/18
    =1 + 1
    =2
    2.
    13/28 xx 5/12 – 5/28 xx 1/12
    =(13/28 – 5/28) xx (5/12 – 1/12)
    = 8/28 xx 4/12
    =(8 xx 4)/(28 xx 12)
    = 2/21
    3.
    19/4 xx 15/23 – 15/4 xx 7/23 + 15/4 xx 11/23
    = 285/92 – 105/92 + 165/92
    = 345/92
    =15/4

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

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