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

Toán Lớp 6: Cho A=5^50 – 5^48 + 5^46 – 5^44 + … + 5^6 – 5^4 + 5^2 – (-1) Tính A

Toán Lớp 6: Cho A=5^50 – 5^48 + 5^46 – 5^44 + … + 5^6 – 5^4 + 5^2 – (-1)
Tính A

Comments ( 1 )

  1. $#Peter$
    A=5^50-5^58+5^46-5^44+…+5^6-5^4+5^2-1
    =>25A=5^2·(5^50-5^58+5^46-5^44+…+5^6-5^4+5^2-1)
    =5^52-5^50+5^58-5^46+5^44+…+5^6+5^4-5^2
    Suy ra : 25A+A=5^52-1
    Vậy  A=(5^52-1):26
     

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