Mister Exam

Other calculators:


x^2/(4-x^2)

Limit of the function x^2/(4-x^2)

at
v

For end points:

The graph:

from to

Piecewise:

The solution

You have entered [src]
     /   2  \
     |  x   |
 lim |------|
x->oo|     2|
     \4 - x /
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right)$$
Limit(x^2/(4 - x^2), x, oo, dir='-')
Detail solution
Let's take the limit
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right)$$
Let's divide numerator and denominator by x^2:
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right)$$ =
$$\lim_{x \to \infty} \frac{1}{-1 + \frac{4}{x^{2}}}$$
Do Replacement
$$u = \frac{1}{x}$$
then
$$\lim_{x \to \infty} \frac{1}{-1 + \frac{4}{x^{2}}} = \lim_{u \to 0^+} \frac{1}{4 u^{2} - 1}$$
=
$$\frac{1}{-1 + 4 \cdot 0^{2}} = -1$$

The final answer:
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right) = -1$$
Lopital's rule
We have indeterminateness of type
oo/-oo,

i.e. limit for the numerator is
$$\lim_{x \to \infty} x^{2} = \infty$$
and limit for the denominator is
$$\lim_{x \to \infty}\left(4 - x^{2}\right) = -\infty$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\frac{d}{d x} x^{2}}{\frac{d}{d x} \left(4 - x^{2}\right)}\right)$$
=
$$\lim_{x \to \infty} -1$$
=
$$\lim_{x \to \infty} -1$$
=
$$-1$$
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]
-1
$$-1$$
Other limits x→0, -oo, +oo, 1
$$\lim_{x \to \infty}\left(\frac{x^{2}}{4 - x^{2}}\right) = -1$$
$$\lim_{x \to 0^-}\left(\frac{x^{2}}{4 - x^{2}}\right) = 0$$
More at x→0 from the left
$$\lim_{x \to 0^+}\left(\frac{x^{2}}{4 - x^{2}}\right) = 0$$
More at x→0 from the right
$$\lim_{x \to 1^-}\left(\frac{x^{2}}{4 - x^{2}}\right) = \frac{1}{3}$$
More at x→1 from the left
$$\lim_{x \to 1^+}\left(\frac{x^{2}}{4 - x^{2}}\right) = \frac{1}{3}$$
More at x→1 from the right
$$\lim_{x \to -\infty}\left(\frac{x^{2}}{4 - x^{2}}\right) = -1$$
More at x→-oo
The graph
Limit of the function x^2/(4-x^2)