Giúp mik `3` câu này nha Tìm `x` ạ

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Giúp mik `3` câu này nha
Tìm `x` ạ

giup-mik-3-cau-nay-nha-tim-a

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Nem 6 years 2020-11-27T23:43:45+00:00 1 Answers 57 views 0

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  1. Acacia
    0
    2020-11-27T23:45:33+00:00
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    a) `3^(-1) .4^x+3. 4^x=5/3 .2^7`

    `⇒ 4^x .(3^(-1) +3)=5/3 .128`

    `⇒ 4^x . 10/3=640/3`

    `⇒ 4^x =640/3÷10/3=64`

    `⇒ 4^x=4^3`

    `⇒ x=3`

    b) `9^(-x) .27^x=243`

    `⇒ 3^(-2x) .3^(3x)=243`

    `⇒ 3^(-2x+3x)=243`

    `⇒ 3^x=3^5`

    `⇒ x=5`

    c) `2^(-2) .2^x+2. 2^x=9.2^6`

    `⇒ 2^x .(2^(-2) +2)=9.64`

    `⇒ 2^x . 9/4=576`

    `⇒ 2^x=576÷9/4`

    `⇒ 2^x=256`

    `⇒ 2^x=2^8`

    `⇒ x=8`

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