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

Toán Lớp 5: `A=1/42+1/30+1/20+1/12+1/6+1/2`

Toán Lớp 5: A=1/42+1/30+1/20+1/12+1/6+1/2

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    A = 1/42 + 1/30 +…….+ 1/6 + 1/2
    A = 1/(1xx2) + 1/(2xx3) +……..+ 1/(5xx6) + 1/(6xx7)
    A = 1 – 1/2 + 1/2 – 1/3 +……..+ 1/5 – 1/6 + 1/6 – 1/7
    A = 1 – 1/7
    A = 6/7

  2. =1/2+1/6+1/12+1/20+1/30+1/42
    =\frac{1}{1.2}+\frac{1}{2.3}+\frac{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}
    =1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
    =1-1/7
    =6/7
     

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

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