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

Toán Lớp 8: 1+2 mũ 2 + 2 mũ 4 + 2 mũ 6 +…..+ 2 mũ 98+ 2 mũ 100

Toán Lớp 8: 1+2 mũ 2 + 2 mũ 4 + 2 mũ 6 +…..+ 2 mũ 98+ 2 mũ 100

Comments ( 2 )

  1. Giải đáp:
    .
    Lời giải và giải thích chi tiết:
    $A=1+2^2+2^4+2^6\ +\,.\!.\!.+\ 2^{100}\\\Rightarrow 2^2A=2^2+2^4+2^6+2^8\ +\,.\!.\!.+\ 2^{102}\\\Rightarrow 4A-A=(2^2+2^4+2^6+2^8\ +\,.\!.\!.+\ 2^{102})-(1+2^2+2^4+2^6\ +\,.\!.\!.+\ 2^{100})\\\Rightarrow 3A=2^{102}-1\\\Rightarrow A=\dfrac{2^{102}-1}{3}$

  2. Đặt A = 1 + $2^{2}$ + $2^{4}$ + $2^{6}$ + … + $2^{98}$ + 2$2^{100}$ 
    ⇒ 4A = 2² + $2^{4}$  + $2^{6}$  + … + $2^{102}$
    ⇒ 4A – A = ( 2² + $2^{4}$ + $2^{6}$ + …. + $2^{102}$ ) – ( 1 + 2² + $2^{4}$  + $2^{6}$ + … +$2^{100}$ )
    ⇒ 3A = $2^{102}$ – 1
    ⇒ A = $\frac{2^{102}-1}{3}$  
    Cho mình câu trả lời hay nhất nhaaaaaaaaa

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