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

Toán Lớp 4: Tính nhanh 49 × 29 – 19 × 47 b. 11 × 763 – 763

Toán Lớp 4: Tính nhanh 49 × 29 – 19 × 47 b. 11 × 763 – 763

Comments ( 2 )

  1. a)
    49 × 29 – 19 × 47
    = 49 × ( 19 + 10 ) – 19 × 47
    = 49 × 19 + 49 × 10 – 19 × 47
    = 19 × ( 49 – 47 ) + 49 × 10
    = 19 × 2 + 490
    = 38 + 490
    = 528
    b)
    11 × 763 – 763
    = 763 × ( 11 – 1)
    = 763 × 10
    = 7630
     

  2. a) 49 xx 29 – 19 xx 47
    = ( 47 + 2 ) xx 29 – 19 xx 47
    = 47 xx 29 + 2 xx 29 – 19 xx 47
    = 47 xx 29 – 47 xx 19 + 2 xx 29
    = 47 xx ( 29 – 19 ) + 2 xx 29
    = 47 xx 10 + 58
    = 470 + 58
    = 528
    b) 11 xx 763 – 763
    = 763 xx ( 11 – 1 )
    = 763 xx 10
    = 7630

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