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

$$\lim_{x\to -\infty}\frac{\sqrt{5x^2-2x^3+9x^6}}{-17+3x+8x^3}
=\lim_{x\to -\infty}\frac{-x^3\sqrt{5\frac{1}{x^4}-2\frac{1}{x^3}+9}}{-17+3x+8x^3}
=\lim_{x\to -\infty}\frac{\sqrt{5\frac{1}{x^4}-2\frac{1}{x^3}+9}}{\frac{17}{x^3}-\frac{3}{x^2}-8}=-\frac{3}{8}$$
