\(2x-x\left(3x+1\right)< 15-3x\left(x+2\right)\)
\(\Leftrightarrow2x-3x^2-x< 15-3x^2-6x\)
\(\Leftrightarrow2x-3x^2-x+3x^2+6x< 15\)
\(\Leftrightarrow7x< 15\)
\(\Leftrightarrow x< \dfrac{15}{7}\)
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\(\dfrac{1-2x}{4}-2\le\dfrac{1-5x}{8}+x\)
\(\Leftrightarrow\dfrac{1-2x}{4}-\dfrac{1-5x}{8}-x\le2\)
\(\Leftrightarrow\dfrac{2\left(1-2x\right)-\left(1-5x\right)}{8}\le2\)
\(\Leftrightarrow2-4x-1+5x\le16\)
\(\Leftrightarrow x\le15\)
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