1
$\lim\limits_{x\to +\infty}\dfrac{1-3x^3+x^2}{5+x-2x^2}$
$=\lim\limits_{x\to +\infty}x.\dfrac{\dfrac{1}{x^3}-3+\dfrac{1}{x} }{\dfrac{5}{x^2}+\dfrac{1}{x}-2}$
$=+\infty$
2.
$\lim\limits_{x\to -\infty}\dfrac{3x^2-x^4+1}{2-x-x^2}$
$=\lim\limits_{x\to -\infty}x^2.\dfrac{ \dfrac{3}{x^2}-1+\dfrac{1}{x^4}}{ \dfrac{2}{x^2}-\dfrac{1}{x}-1}$
$=+\infty$