Question

|9+x|=2x

Answer 1

\(\left|9+x\right|=2x\left(đk:x\ge0\right)\)

\(\Leftrightarrow9+x=2x\)

\(\Leftrightarrow x=9\)

 

Answer 2

\(|9+x|=2x\)

<=> \(\left[{}\begin{matrix}9+x=2x\\9+x=-2x\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)

Answer 3

I 9+xI = 2x

=>  Th1 : 9 + x = 2x 

             ⇔ x-2x = -9

             ⇔ -x = -9

            ⇔  x= 9

TH2  I9 +xI = -2x

    ⇔ x +2x = -9

   ⇔ 3x = -9

  ⇔  x = -3

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