\(\lim\limits_{x\rightarrow-\infty}\dfrac{\sqrt{x^2-2x+4}}{3x-1}\)
\(=\lim\limits_{x\rightarrow-\infty}\dfrac{-x\cdot\sqrt{1-\dfrac{2}{x}+\dfrac{4}{x^2}}}{x\cdot\left(3-\dfrac{1}{x}\right)}\)
\(=\lim\limits_{x\rightarrow-\infty}\dfrac{-\sqrt{1-\dfrac{2}{x}+\dfrac{4}{x^2}}}{3-\dfrac{1}{x}}\)
\(=\dfrac{-\sqrt{1-2\cdot0+4\cdot0}}{3-0}=\dfrac{-1}{3}\)