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

Toán Lớp 6: Cho A=2+2²+2³+…+2⁶⁰.Chứng minh rằng a chia hết có 3, cho 7. Giúp em với ạ em cảm ơn nhiều

Toán Lớp 6: Cho A=2+2²+2³+…+2⁶⁰.Chứng minh rằng a chia hết có 3, cho 7. Giúp em với ạ em cảm ơn nhiều

Comments ( 2 )

  1. C/M: A$\vdots$3
    A=2+2²+2³+…+2⁶⁰
    A=(2+2²)+2³+…+($2^{59}$ + 2⁶⁰)
    A=(2+2²)+(2³+$2^{4}$)+…+($2^{59}$ + 2⁶⁰)
    A=2.(1+2)+$2^{3}$.(1+2)+…+$2^{59}$.(1+2)
    A=2.3+$2^{3}$.3+…+$2^{59}$.3
    A=(2+$2^{3}$+…+$2^{59}$).3
    => A$\vdots$3
    C/M: A$\vdots$3
    A=2+2²+2³+…+2⁶⁰
    A=(2+2²+2³)+…+($2^{58}$+$2^{59}$ + 2⁶⁰)
    A=2.(1+2+2²)+…+$2^{58}$.(1+2+)
    A=2.7+…+$2^{58}$.7
    A=(2+…+$2^{58}$).7
    => A$\vdots$7
    CHO MK XIN CTLHN NHA

  2. A=2+2²+2³+…+2⁶⁰
    A=(2+2²)+(2³+2⁴)+…+(2⁵⁹+2⁶⁰)
    A=2(1+2)+2³(1+2)+…+2⁵⁹(1+2)
    A=2.3+2³.3+…+2⁵⁹.3
    A=3(2+2³+…+2⁵⁹)
    ⇒ A $\vdots$ 3
    A=2+2²+2³+…+2⁶⁰
    A=(2+2²+2³)+(2⁴+2⁵+2⁶)+…+(2⁵⁸+2⁵⁹+2⁶⁰)
    A=2(1+2+2²)+2⁴(1+2+2²)+…+2⁵⁸(1+2+2²)
    A=2.7+2⁴.7+…+2⁵⁸.7
    A=7(2+2⁴+…+2⁵⁸)
    ⇒ A $\vdots$ 7

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

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