# Homework Help: Question about a limit

1. Sep 28, 2011

### CrossFit415

x$\stackrel{Lim}{\rightarrow}$infinity ($\sqrt{x^{2}+1}$)$-1$

Couldn't I just inset 0 for x and end up getting $\sqrt{1}$?

The book tells me to rewrite this problem by its conjugate.

My question is why? Thanks

Last edited: Sep 28, 2011
2. Sep 28, 2011

### Staff: Mentor

As you have written it,
$$\lim_{x \to \infty}\sqrt{x^2 + 1} - 1 = \infty$$
You seem to be a little confused in this problem. Why would you put in zero for x when the limit is as x goes to infinity?