Tìm giới hạn 1. lim [{căn(x^5+x-11)} / {2x^2+x+1}] x–>+vô cực 2. lim [{căn3(x^3+2x^2+1)} / {căn(1-2x)}] x–>-vô cự

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1. $1)\displaystyle\lim_{x \to \infty} \dfrac{\sqrt{x^5+x-11}}{2x^2+x+1}\\ =\displaystyle\lim_{x \to \infty} \dfrac{\sqrt{x+\dfrac{1}{x^3}-\dfrac{11}{x^4}}}{2+\dfrac{1}{x}+\dfrac{1}{x^2}}\\ =\displaystyle\lim_{x \to \infty} \dfrac{\sqrt{x}}{2}\\ =\infty\\  2)\displaystyle\lim_{x \to -\infty} \dfrac{\sqrt[3]{x^3+2x^2+1}}{1-2x}\\ =\displaystyle\lim_{x \to -\infty} \dfrac{x\sqrt[3]{1+\dfrac{2}{x}+\dfrac{1}{x^3}}}{1-2x}\\ =\displaystyle\lim_{x \to -\infty} \dfrac{x}{1-2x}\\ =\displaystyle\lim_{x \to -\infty} \dfrac{1}{\dfrac{1}{x}-2}\\ =\dfrac{-1}{2}$

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