Tìm x biết: $\frac{2x-1}{7}$ = $\frac{9}{2x-1}$

Question

Tìm x biết:
$\frac{2x-1}{7}$ = $\frac{9}{2x-1}$

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Khang Minh 5 years 2020-10-24T19:06:04+00:00 2 Answers 88 views 0

Answers ( )

  1. giahuy
    0
    2020-10-24T19:07:58+00:00
    Reply

    Đáp án: $x$ $∈$ `{\frac{\sqrt{63}+1}{2};\frac{-\sqrt{63}+1}{2}}`.

    Giải thích các bước giải:

    `{2x-1}/7 = 9/{2x-1}`

    `⇔ (2x-1).(2x-1) = 7.9`

    `⇔ (2x-1)^2 = 63`

    `⇔ 2x-1 = ±\sqrt{63}`

    `⇒` \(\left[ \begin{array}{l}2x=\sqrt{63}+1\\2x=-\sqrt{63}+1\end{array} \right.\) 

    $⇒$ \(\left[ \begin{array}{l}x=\dfrac{\sqrt{63}+1}{2}\\x=\dfrac{-\sqrt{63}+1}{2}\end{array} \right.\) 

       Vậy $x$ $∈$ `{\frac{\sqrt{63}+1}{2};\frac{-\sqrt{63}+1}{2}}`.

     

  2. Doris
    0
    2020-10-24T19:08:03+00:00
    Reply

    Đáp án:

     

    Giải thích các bước giải:

     `(2x-1)/7=9/(2x-1)`

    `=>(2x-1)^2=7.9=63`

    `=>2x-1=+-sqrt{63}`

    `=>x=(+-sqrt{63}+1)/2`

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )