Limit approaching negative infinity question? 
I'm not sure how to solve this problem.. How do I get rid of the square root?

Setting $h=-\dfrac1x,$
$$F=\lim_{x\to -\infty}\frac{\sqrt{5x^2-2x^3+9x^6}}{-17+3x+8x^3}$$
$$=\lim_{h\to0^+}\frac{\sqrt{5h^4-2h^3+9}/\sqrt{h^6}}{(-17h^3+3h^2+8)/h^3}$$
As $h>0,h\ne0$ and $\sqrt{h^6}=+h^3$
$$F=\frac{\sqrt{5\cdot0^4-2\cdot0^3+9}}{-17\cdot0^3+3\cdot0^2+8}=?$$
