giải phương trình |x+1|-2x=12

`| x + 1 | - 2x = 12`

`<=> | x + 1 | = 12 + 2x` ĐK: `12 + 2x ≥ 0 => 2x ≥ - 12 => x ≥ -6`

`<=>` \(\left[ \begin{array}{l}x+1=12+2x\\x+1=-12-2x\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x-2x=12-1\\x+2x=-12-1\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}-x=11\\3x=-13\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=-11 (ktm) \\x=\frac{-13}{3} (tm)\end{array} \right.\)  
Vậy `S={-13/3}`

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