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

Toán Lớp 6: 2+2 x 2+2x2x2+2x2x2x2+…+2×2…2×2 \=====-/

Toán Lớp 6: 2+2 x 2+2x2x2+2x2x2x2+…+2×2…2×2
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10 thừa số 2

Comments ( 2 )

  1. A = 2 + 2 xx 2 + 2 xx 2 xx 2 +…+ \underbrace{2 xx 2 xx…xx 2}_text{10 chữ số 2}
    A = 2 xx 2^{2} + 2^{3} +…+ 2^{10}
    2A = 2 xx (2 xx 2^{2} + 2^{3} +…+ 2^{10})
    2A = 2^{2} + 2^{3} + 2^{4} + … + 2^{11}
    2A – A = (2^{2} + 2^{3} + 2^{4} + … + 2^{11}) – (2 + 2^{2} + 2^{3} +…+ 2^{10})
    A = 2^{11} – 2
    A=2046

  2. A = 2+2 x 2+2x2x2+2x2x2x2+…+2×2…2×2
                                                  \——–/ 10 thừa số 2
    = 2 + $2^{2}$  + $2^{3}$ + $2^{4}$ + …….. + $2^{10}$
    ⇒ 2A = $2^{2}$  + $2^{3}$ + $2^{4}$ + …….. + $2^{10}$ + $2^{11}$
    ⇒ 2A – A = A = ($2^{2}$  + $2^{3}$ + $2^{4}$ + …….. + $2^{10}$ + $2^{11}$) – (2 + $2^{2}$  + $2^{3}$ + $2^{4}$ + …….. + $2^{10}$)
    =$2^{11}$ -2

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