1. lim (x^{4} - 5x^{3} + 8x^{2} -6x +3)
2. \mathop {\lim }\limits_{x \to 2^{+}} \sqrt{x^{3} +x^{2} -6x}
3. \mathop {\lim }\limits_{x \to -1} \sqrt[2012]{\frac{3x^{2} - 5x + 4}{x - 2} +3x +8}
4. \mathop {\lim }\limits_{x \to -1} ( \sqrt[4]{\frac{x}{x - 2}} + \sqrt[3]{\frac{x + 2}{x}})