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

Toán Lớp 5: bài 1:tính nhanh:A=1+1/3+1/6+1/12+1/24+1/48 bài 2:tính nhanh:E=1/2+3/4+7/8+15/16+31/32+63/64 bài 3:tính nhanh: G=5/6+11/12

Toán Lớp 5: bài 1:tính nhanh:A=1+1/3+1/6+1/12+1/24+1/48 bài 2:tính nhanh:E=1/2+3/4+7/8+15/16+31/32+63/64 bài 3:tính nhanh: G=5/6+11/12+19/20+29/30+41/42+55/56

Comments ( 1 )

  1. text{Giải đáp + Lời giải và giải thích chi tiết:}
    text{Bài 1 : }
    A = 1 + 1/3 + 1/6 + 1/12 + 1/24 + 1/48
    3A = 3 + 1 + 1/2 + 1/4 + 1/8 + 1/16
    3A = 3 + 3 – 1 + 1 – 1/2 + 1/2 – 1/4 + 1/4 – 1/8 + 1/8 – 1/16
    => 3A = 3 + 3 – 1/16
    => 3A = 6 – 1/16
    => A = ( 6 – 1/16) : 3
    => A = 95/16
    text{Bài 2 : }
    S=1/2+3/4+7/8+15/16+31/32+63/64
    S= 1-1/2 + 1-1/4 + 1-1/8 + 1-1/16 + 1-1/32 + 1-1/64
    S= (1+1+1+1+1+1) – (1/2+1/4+1/8+1/16 + 1/32+1/64)
    S = 6 – 63/64
    S = 5 1/64
    text{Bài 3 : }
    G = 5/6 + 11/12 + 19/20 + 29/30 + 41/42 + 55/56
    G = ( 5/6 + 11/12 ) + ( 19/20 + 29/30 ) + ( 41/42 + 55/56)
    G = ( 10/12 + 11/12 ) + ( 570/600 + 580/600 ) + ( 2296/2352 + 2310/2353 )
    G = 21/12 + 1250/600 + 4606/2353
    G = 7/6 + 25/12 + 4606/2353
    G = 14/12 + 25/12 + 4606/2353
    G = 39/12 + 4606/2353
    G = 45/8

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

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