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asin(2*x)/(4*x)

Limit of the function asin(2*x)/(4*x)

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     /asin(2*x)\
 lim |---------|
x->0+\   4*x   /
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
Limit(asin(2*x)/((4*x)), x, 0)
Detail solution
Let's take the limit
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
Do replacement
$$u = \operatorname{asin}{\left(2 x \right)}$$
$$x = \frac{\sin{\left(u \right)}}{2}$$
we get
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{\lim_{u \to 0^+}\left(\frac{\operatorname{asin}{\left(\frac{2 \sin{\left(u \right)}}{2} \right)}}{\frac{1}{2} \sin{\left(u \right)}}\right)}{4}$$
=
$$\frac{\lim_{u \to 0^+}\left(\frac{2 \operatorname{asin}{\left(\sin{\left(u \right)} \right)}}{\sin{\left(u \right)}}\right)}{4} = \frac{\lim_{u \to 0^+}\left(\frac{2 u}{\sin{\left(u \right)}}\right)}{4}$$
=
$$\frac{\lim_{u \to 0^+} \frac{1}{\frac{1}{u} \sin{\left(u \right)}}}{2}$$
               /sin(u)\  
= 1/2 / (  lim |------| )
          u->0+\  u   /  

The limit
$$\lim_{u \to 0^+}\left(\frac{\sin{\left(u \right)}}{u}\right)$$
is first remarkable limit, is equal to 1.

The final answer:
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{1}{2}$$
Lopital's rule
We have indeterminateness of type
0/0,

i.e. limit for the numerator is
$$\lim_{x \to 0^+} \operatorname{asin}{\left(2 x \right)} = 0$$
and limit for the denominator is
$$\lim_{x \to 0^+}\left(4 x\right) = 0$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
=
Let's transform the function under the limit a few
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \operatorname{asin}{\left(2 x \right)}}{\frac{d}{d x} 4 x}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{1}{2 \sqrt{1 - 4 x^{2}}}\right)$$
=
$$\lim_{x \to 0^+} \frac{1}{2}$$
=
$$\lim_{x \to 0^+} \frac{1}{2}$$
=
$$\frac{1}{2}$$
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
One‐sided limits [src]
     /asin(2*x)\
 lim |---------|
x->0+\   4*x   /
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
1/2
$$\frac{1}{2}$$
= 0.5
     /asin(2*x)\
 lim |---------|
x->0-\   4*x   /
$$\lim_{x \to 0^-}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
1/2
$$\frac{1}{2}$$
= 0.5
= 0.5
Rapid solution [src]
1/2
$$\frac{1}{2}$$
Other limits x→0, -oo, +oo, 1
$$\lim_{x \to 0^-}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{1}{2}$$
More at x→0 from the left
$$\lim_{x \to 0^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{1}{2}$$
$$\lim_{x \to \infty}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
More at x→oo
$$\lim_{x \to 1^-}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{\operatorname{asin}{\left(2 \right)}}{4}$$
More at x→1 from the left
$$\lim_{x \to 1^+}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right) = \frac{\operatorname{asin}{\left(2 \right)}}{4}$$
More at x→1 from the right
$$\lim_{x \to -\infty}\left(\frac{\operatorname{asin}{\left(2 x \right)}}{4 x}\right)$$
More at x→-oo
Numerical answer [src]
0.5
0.5
The graph
Limit of the function asin(2*x)/(4*x)