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2*x/(1-x^2)

Limit of the function 2*x/(1-x^2)

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     / 2*x  \
 lim |------|
x->oo|     2|
     \1 - x /
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right)$$
Limit((2*x)/(1 - x^2), x, oo, dir='-')
Detail solution
Let's take the limit
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right)$$
Let's divide numerator and denominator by x^2:
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right)$$ =
$$\lim_{x \to \infty}\left(\frac{2 \frac{1}{x}}{-1 + \frac{1}{x^{2}}}\right)$$
Do Replacement
$$u = \frac{1}{x}$$
then
$$\lim_{x \to \infty}\left(\frac{2 \frac{1}{x}}{-1 + \frac{1}{x^{2}}}\right) = \lim_{u \to 0^+}\left(\frac{2 u}{u^{2} - 1}\right)$$
=
$$\frac{0 \cdot 2}{-1 + 0^{2}} = 0$$

The final answer:
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right) = 0$$
Lopital's rule
We have indeterminateness of type
oo/-oo,

i.e. limit for the numerator is
$$\lim_{x \to \infty}\left(2 x\right) = \infty$$
and limit for the denominator is
$$\lim_{x \to \infty}\left(1 - x^{2}\right) = -\infty$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right)$$
=
Let's transform the function under the limit a few
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\frac{d}{d x} 2 x}{\frac{d}{d x} \left(1 - x^{2}\right)}\right)$$
=
$$\lim_{x \to \infty}\left(- \frac{1}{x}\right)$$
=
$$\lim_{x \to \infty}\left(- \frac{1}{x}\right)$$
=
$$0$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)
The graph
Rapid solution [src]
0
$$0$$
Other limits x→0, -oo, +oo, 1
$$\lim_{x \to \infty}\left(\frac{2 x}{1 - x^{2}}\right) = 0$$
$$\lim_{x \to 0^-}\left(\frac{2 x}{1 - x^{2}}\right) = 0$$
More at x→0 from the left
$$\lim_{x \to 0^+}\left(\frac{2 x}{1 - x^{2}}\right) = 0$$
More at x→0 from the right
$$\lim_{x \to 1^-}\left(\frac{2 x}{1 - x^{2}}\right) = \infty$$
More at x→1 from the left
$$\lim_{x \to 1^+}\left(\frac{2 x}{1 - x^{2}}\right) = -\infty$$
More at x→1 from the right
$$\lim_{x \to -\infty}\left(\frac{2 x}{1 - x^{2}}\right) = 0$$
More at x→-oo
The graph
Limit of the function 2*x/(1-x^2)