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Jeff Bezos

19/03/2017 at 10:27
Answers
2
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Find the values of x for |2x-3| + |2x+1| = 4


absolute value


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    Phan Thanh Tinh Coordinator 23/03/2017 at 20:31

    Case 1 :\(x< -\dfrac{1}{2}\Leftrightarrow\left\{{}\begin{matrix}2x-3< -4< 0\\2x+1< 0\end{matrix}\right.\)

    \(\Rightarrow3-2x-2x-1=4\Rightarrow4x=-2\Rightarrow x=-\dfrac{1}{2}\)(asburd)

    Case 2 :\(-\dfrac{1}{2}\le x< \dfrac{3}{2}\Rightarrow\left\{{}\begin{matrix}2x-3< 0\\2x+1\ge0\end{matrix}\right.\)

    \(\Rightarrow3-2x+2x+1=4\Rightarrow4=4\) (true)

    Case 3 :\(x\ge\dfrac{3}{2}\Rightarrow\left\{{}\begin{matrix}2x-3\ge0\\2x+1\ge4>0\end{matrix}\right.\)

    \(\Rightarrow2x-3+2x+1=4\Rightarrow4x-2=4\Rightarrow4x=6\Rightarrow x=\dfrac{3}{2}\)(true)

    So\(-\dfrac{1}{2}\le x\le\dfrac{3}{2}\)

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    ¤« 08/04/2018 at 15:12

    Case 1 :x<−12⇔{2x−3<−4<02x+1<0

    ⇒3−2x−2x−1=4⇒4x=−2⇒x=−12

    (asburd)

    Case 2 :−12≤x<32⇒{2x−3<02x+1≥0

    ⇒3−2x+2x+1=4⇒4=4

     (true)

    Case 3 :x≥32⇒{2x−3≥02x+1≥4>0

    ⇒2x−3+2x+1=4⇒4x−2=4⇒4x=6⇒x=32

    (true)

    So−12≤x≤32


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