# Math Help - Limit At Infinity of Absolute Value Function

1. ## Limit At Infinity of Absolute Value Function

Along with many other things (namely, finding concavity, increasing/decreasing, inflection, etc.), my teacher assigned to me to find any horizontal asymptotes by using limits at infinity. The function I was given is y = |x^4-9x^2|. I am not exactly certain how to do this sort of thing with absolute value. I end up with
|infinity^4 - 9infinity^2|, and isn't this some sort of indeterminant form?

2. ## Re: Limit At Infinity of Absolute Value Function

y = $|x^4-9x^2| = |x^2(x^2-9)|$

for $x \ge 3$ or $x \le -3$ , $y = x^2(x^2-9)$

so ... what does happens to y as x gets very large (+) or (-) ?