# Thread: How to deal with undefined limits?

1. ## How to deal with undefined limits?

$\text{For}\displaystyle \lim_{x \to \infty} \frac{\sin{x}}{x}=\lim_{x \to \infty} \frac{1}{x}\times \lim_{x \to \infty} \sin{x}=0 \times \text{Unknown}$

2. Originally Posted by crossbone
$\text{For}\displaystyle \lim_{x \to \infty} \frac{\sin{x}}{x}=\lim_{x \to \infty} \frac{1}{x}\times \lim_{x \to \infty} \sin{x}=0 \times \text{Unknown}$

$-1\ \le\ sinx\ \le\ 1$

$\displaystyle\lim_{x \to \infty}\ \left(-\frac{1}{x}\right)\ \le\ \lim_{x \to \infty}\frac{sin\;x}{x}\ \le\ \lim_{x \to \infty}\left(\frac{1}{x}\right)$

3. Thanks! just curious, what's the answer to $\displaystyle \lim_{x \to \infty} sin\;x \$? Undefined?

4. Originally Posted by crossbone
Thanks! just curious, what's the answer to $\displaystyle \lim_{x \to \infty} sin\;x \$? Undefined?
Yes that limit is not defined.

5. Thanks! btw, what are indeterminate forms as far as limits is concern?
$\frac{0}{0}, \frac{\infty}{\infty}, \frac{0}{\infty}, \frac{\infty}{0}, \infty \times 0$?

6. Originally Posted by crossbone
Thanks! just curious, what's the answer to $\displaystyle \lim_{x \to \infty} sin\;x \$? Undefined?
Can you apply the squeeze theorem to $\displaystyle\lim_{x \to \infty}\frac{sin\;x}{x}\;\;?$

Edit: sorry, the absence of a denominator bypassed my vision!
Thanks Plato
(next post).

7. Originally Posted by Archie Meade
Can you apply the squeeze theorem to $\displaystyle\lim_{x \to \infty}\sin(x)?$
Not to that limit. It bounces from -1 to 1.