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

Toán Lớp 5: giup mk vs dag can gap : a+1+b+1+a+1+b+1+a+1+b+1 (biết a = 3-b)

Toán Lớp 5: giup mk vs dag can gap : a+1+b+1+a+1+b+1+a+1+b+1 (biết a = 3-b)

Comments ( 2 )

  1. Vì a = 3 – b nên a + b = 3
    Ta có : a + 1 + b + 1 + a + 1 + b + 1 + a + 1 + b + 1
    = ( a + a + a ) + ( b + b + b ) + ( 1 + 1 + 1 + 1 + 1 + 1 )
    = 3 xx a + 3 xx b + 1 xx 6
    = 3 xx ( a + b ) + 6
    Mà a + b = 3 nên ta được : 3 xx ( a + b ) + 6
    = 3 xx 3 + 6
    = 9 + 6
    = 15
     

  2. a + 1 + b + 1 + a + 1 + b + 1 + a + 1 + b + 1
    = ( a × 3 ) + ( b × 3 ) + ( 1 + 1 + 1 + 1 + 1 + 1 )
    = ( a + b ) × 3 + 6
    Mà a = 3 – b => a + b = 3
    Ta có :
    3 × 3 + 6
    = 9 + 6
    = 15
    Vậy a + 1 + b + 1 + a + 1 + b + 1 + a + 1 + b + 1 = 15
    #dtkc

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