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