$\lim_{x\to-\infty}\frac{1-5x^2}{3+4x+x^5}$

$f\left(x\right)=3x^3-9x$

$\frac{x^2-8}{x+3}$

$\lim_{\theta\to\frac{\pi}{4}\frac{\cos\left(2\theta\right)}{\sqrt{2}\cos\left(\theta\right)-1}}$

$\left(3x^2+7y^3\right)\left(9x^4-21x^2y^3+49y^6\right)$

$\frac{4x^3-2x^2-14x-2}{2x+3}$

$1-7+2$