tìm x, thỏa mãn: a, (2x-3).(x-1)>0 b, (3x+1).(x-2)<0 mng mn giải giúp mk ạ.......!

Question

tìm x, thỏa mãn:
a, (2x-3).(x-1)>0
b, (3x+1).(x-2)<0 mng mn giải giúp mk ạ.......!

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Piper 3 tuần 2021-08-21T17:04:22+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-08-21T17:05:36+00:00

    Giải thích các bước giải:

     a) `(2x-3)(x-1)>0`

    `=>2x-3;x-1` cùng dấu

    `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}2x-3>0\\x-1>0\end{matrix}\right.\\\left\{\begin{matrix}2x-3<0\\x-1<0\end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}2x>3\\x>1\end{matrix}\right.\\\left\{\begin{matrix}2x<3\\x<1\end{matrix}\right.\end{array} \right.\)`=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x>\dfrac{3}{2}\\x>1\end{matrix}\right.\\\left\{\begin{matrix}x<\dfrac{3}{2}\\x<1\end{matrix}\right.\end{array} \right.\)`=>`\(\left[ \begin{array}{l}x>\dfrac{3}{2}\\x<1\end{array} \right.\)

        Vậy `x>3/2` hoặc `x<1.`

     b) `(3x+1).(x-2)<0`

    `=>3x+1;x-2` trái dấu

    `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}3x+1>0\\x-2<0\end{matrix}\right.\\\left\{\begin{matrix}3x+1<0\\x-2>0\end{matrix}\right.\end{array} \right.\) `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}3x>-1\\x<2\end{matrix}\right.\\\left\{\begin{matrix}3x<-1\\x>2\end{matrix}\right.\end{array} \right.\)

    `=>`\(\left[ \begin{array}{l}\left\{\begin{matrix}x>-\dfrac{1}{3}\\x<2\end{matrix}\right.\\\left\{\begin{matrix}x<-\dfrac{1}{3}\\x>2\end{matrix}\right.\text{(loại)}\end{array} \right.\)`=>-1/3<x<2`

        Vậy `-1/3<x<2.`

    0
    2021-08-21T17:06:05+00:00

    Đáp án:

     

    Giải thích các bước giải:

     Mk gửi ảnh r đó

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