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

Toán Lớp 9: Rút gọn: 1 – 5 + 5^2 + 5^3 + … + 5^99 + 5^100

Toán Lớp 9: Rút gọn: 1 – 5 + 5^2 + 5^3 + … + 5^99 + 5^100

Comments ( 1 )

  1. Giải đáp:
     A=1-5+5²-5³+…-$5^{99}$+$5^{100}$
       =1+$(-5)^{1}$+$(-5)^{2}$ +$(-5)^{3}$ +…+$(-5)^{100}$
    A-(-5).A=[1+(-5)+$(-5)^{2}$ +…+$(-5)^{100}$]-[(-5)+$(-5)^{2}$ +$(-5)^{101}$]
    ⇒A.(-5-1)=$(-5)^{101}$-1
    ⇒A[1-(-5)] =1-$(-5)^{101}$ 
    ⇒6.A=1+$5^{101}$ 
    ⇒A= $\frac{1+5^{101}}{6}$

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

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