\(\left|2x+4\right|+\left|5x+10\right|=\left|2\left(x+2\right)\right|+\left|5\left(x+2\right)\right|\ge\left|2\left(x+2\right)+5\left(x+2\right)\right|=\left|7\left(x+2\right)\right|\)
Từ đó: \(\left|7\left(x+2\right)\right|\le\dfrac{5}{7}\)
\(\Leftrightarrow\left\{{}\begin{matrix}7\left(x+2\right)\le\dfrac{5}{7}\\7\left(x+2\right)\ge-\dfrac{5}{7}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x+2\le\dfrac{5}{49}\\x+2\ge-\dfrac{5}{49}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x\le-\dfrac{93}{49}\\x\ge-\dfrac{103}{49}\end{matrix}\right.\)
\(\Rightarrow\dfrac{-103}{49}\le x\le-\dfrac{93}{49}\)
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