\(D=4x-\sqrt{9x^2-12x+4}\)
\(D=4x-\sqrt{\left(3x-2\right)^2}\)
\(D=4x-\) /3x - 2 /
* 3x - 2 \(\ge0\) \(\Leftrightarrow3x\ge2\Leftrightarrow x\ge\dfrac{2}{3}\)
=> D = 4x - 3x +2 = x + 2
* 3x - 2 \(\le0\Leftrightarrow3x\le2\Leftrightarrow x\le\dfrac{2}{3}\)
=> D = 4x + 3x - 2 = 7x - 2
Vậy \(\left[{}\begin{matrix}D=x+2\\D=7x-2\end{matrix}\right.\)
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D=\(4x-\sqrt{9x^2-12x+\text{4}}\)
\(=4x-\sqrt{\left(3x-2\right)^2}\)
\(=4x-\left|3x-2\right|\)
\(=4x-3x+2\)
\(=x+2\)
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