1.
$\lim\limits_{x\to +\infty}\dfrac{(x+1)(3-2x-5x^3) }{x(x^3-1)}$
$=\lim\limits_{x\to +\infty}\dfrac{(1+\dfrac{1}{x})(\dfrac{3}{x^3}-\dfrac{2}{x^2}-5)}{1-\dfrac{1}{x^3}}$
$=-5$
2.
$\lim\limits_{x\to -\infty}\dfrac{(2x^2+1)(2x^2+x)}{(2x^4+x)(x+1)}$
$=\lim\limits_{x\to -\infty}\dfrac{1}{x}.\dfrac{(2+\dfrac{1}{x^2})(2+\dfrac{1}{x}) }{(2+\dfrac{1}{x^3})(1+\dfrac{1}{x})}$
$=0$