tìm x: 5*4^x+1-20=3(10^5:10^3)

Question

tìm x:
5*4^x+1-20=3(10^5:10^3)

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Adela 6 years 2020-10-14T12:22:01+00:00 2 Answers 120 views 0

Answers ( )

  1. Dulcie
    0
    2020-10-14T12:23:24+00:00
    Reply

    Đáp án:

     $x=2$

    Giải thích các bước giải:

     $5.4^{x+1}-20=3.(10^5:10^3)$

    $⇒5.4.4^x-20=3.10^2$

    $⇒20.4^x-20=300$

    $⇒20.4^x=320$

    $⇒4^x=16$

    $⇒4^x=4^2$

    $⇒x=2$

  2. kiet
    0
    2020-10-14T12:23:55+00:00
    Reply

    Đáp án: 

    5×4^x+1-20=3(10^5 :`10^3)

    5×4^x+1-20=3.10^2

    5×4^x+1-20=3×100

    5×4^x+1-20=300

    5×4^x-1=320

    5×4^x-1=320

    4^x-1=320:5

    4^x-1=64

    4^x-1=4^3

    ⇒x-1=3

    ⇒x=3-1

    ⇒x=2

    Vậy x=2

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