A={2+2mũ2+2mũ3+2mũ4+… +2mũ20

Question

A={2+2mũ2+2mũ3+2mũ4+… +2mũ20

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Cherry 4 years 2020-10-31T07:25:52+00:00 2 Answers 133 views 0

Answers ( )

    0
    2020-10-31T07:27:35+00:00

    Đáp án: A=2^20-2

     

    Giải thích các bước giải:

     A=2+2^2+2^3+2^4+…+2^20

    2.A=2^2+2^3+2^4+…+2^20

    2.A-A=(2^2+2^3+2^4+…+2^20)

              – (-2+2^2+2^3+2^4+2^20

    A=2^20-2

    Cho mk xin ctlhn

    0
    2020-10-31T07:27:47+00:00

    `A = 2+2²+2³+2^4 + … + 2^20`

    `⇒ 2A = 2² + 2³ + 2^4 + 2^5  + … + 2^21`

    `⇒ 2A – A = (2² + 2³ + 2^4 + 2^5  + … + 2^21) – (2+2²+2³+2^4 + … + 2^20)`

    `⇒ A = 2^21 – 2`

    Xin hay nhất !

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