Why can $y=0$ be considered the asymptote of $f(x)=fracsin xx$?
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Why can $y=0$ be considered the asymptote of $f(x)=fracsin xx$ when the two graphs don't get any closer when $x$ approaches infinity? Because isn't the asymptote something that a graph will touch and stay on once the graph reaches infinity? And yet, in $f(x)=fracsin xx$, the size of $x$ has no effect on the graph's proximity to the asymptote. It just keeps fluctuating around $y=0$! So that suggests that the graph won't touch and stay on the asymptote at infinity? And if it doesn't, how can $y=0$ still be considered the asymptote of $f(x)=fracsin xx$?
algebra-precalculus asymptotics
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up vote
3
down vote
favorite
Why can $y=0$ be considered the asymptote of $f(x)=fracsin xx$ when the two graphs don't get any closer when $x$ approaches infinity? Because isn't the asymptote something that a graph will touch and stay on once the graph reaches infinity? And yet, in $f(x)=fracsin xx$, the size of $x$ has no effect on the graph's proximity to the asymptote. It just keeps fluctuating around $y=0$! So that suggests that the graph won't touch and stay on the asymptote at infinity? And if it doesn't, how can $y=0$ still be considered the asymptote of $f(x)=fracsin xx$?
algebra-precalculus asymptotics
1
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
1
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
4
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
1
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38
add a comment |Â
up vote
3
down vote
favorite
up vote
3
down vote
favorite
Why can $y=0$ be considered the asymptote of $f(x)=fracsin xx$ when the two graphs don't get any closer when $x$ approaches infinity? Because isn't the asymptote something that a graph will touch and stay on once the graph reaches infinity? And yet, in $f(x)=fracsin xx$, the size of $x$ has no effect on the graph's proximity to the asymptote. It just keeps fluctuating around $y=0$! So that suggests that the graph won't touch and stay on the asymptote at infinity? And if it doesn't, how can $y=0$ still be considered the asymptote of $f(x)=fracsin xx$?
algebra-precalculus asymptotics
Why can $y=0$ be considered the asymptote of $f(x)=fracsin xx$ when the two graphs don't get any closer when $x$ approaches infinity? Because isn't the asymptote something that a graph will touch and stay on once the graph reaches infinity? And yet, in $f(x)=fracsin xx$, the size of $x$ has no effect on the graph's proximity to the asymptote. It just keeps fluctuating around $y=0$! So that suggests that the graph won't touch and stay on the asymptote at infinity? And if it doesn't, how can $y=0$ still be considered the asymptote of $f(x)=fracsin xx$?
algebra-precalculus asymptotics
edited Jul 23 at 17:11


peterh
2,14731631
2,14731631
asked Jul 23 at 14:31


Ethan Chan
603322
603322
1
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
1
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
4
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
1
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38
add a comment |Â
1
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
1
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
4
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
1
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38
1
1
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
1
1
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
4
4
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
1
1
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38
add a comment |Â
4 Answers
4
active
oldest
votes
up vote
7
down vote
There are several misconceptions in your post.
$$fracsin xx$$ does get closer and closer to $0$ when $x$ increases. In fact,
$$left|fracsin xxright|lefrac1x$$ and the RHS clearly tends to $0$.
"... isn't the asymptote something that a graph will touch and stay on ...": no, quite often an asymptote doesn't touch the curve. It just needs to come arbitrarily close. In the case at hand, it crosses it infinitely often, but this does not matter.
add a comment |Â
up vote
4
down vote
I have already written to you about this. Look at the graph of your function:
Don't you agree that, as we move to the right, the graph gets closer to $0$? To be more precise, if we fix a number $varepsilon>0$, then, if $M$ is large enough, the graph of the restriction of $f$ to $[M,+infty)$ is between the lines $y=varepsilon$ and $y=-varepsilon$. That's what it means that the line $y=0$ is an asymptote of the graph of $f$.
add a comment |Â
up vote
2
down vote
The definition of an horizontal asymptote is that
$$limlimits_x to infty f(x) = c.$$
Which is exactly the case here with $c=0$.
In no way the definition of an asymptote implies that the function is supposed to stay on the same side of the asymptote for $x$ large enough.
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
add a comment |Â
up vote
1
down vote
f(x)=sinx/x, the size of x has no effect on the graph's proximity to the asymptote.
Yes it does:
$$textmax_x>x_0left|fracsin(x)x-0right|leq frac1x_0$$
add a comment |Â
4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
7
down vote
There are several misconceptions in your post.
$$fracsin xx$$ does get closer and closer to $0$ when $x$ increases. In fact,
$$left|fracsin xxright|lefrac1x$$ and the RHS clearly tends to $0$.
"... isn't the asymptote something that a graph will touch and stay on ...": no, quite often an asymptote doesn't touch the curve. It just needs to come arbitrarily close. In the case at hand, it crosses it infinitely often, but this does not matter.
add a comment |Â
up vote
7
down vote
There are several misconceptions in your post.
$$fracsin xx$$ does get closer and closer to $0$ when $x$ increases. In fact,
$$left|fracsin xxright|lefrac1x$$ and the RHS clearly tends to $0$.
"... isn't the asymptote something that a graph will touch and stay on ...": no, quite often an asymptote doesn't touch the curve. It just needs to come arbitrarily close. In the case at hand, it crosses it infinitely often, but this does not matter.
add a comment |Â
up vote
7
down vote
up vote
7
down vote
There are several misconceptions in your post.
$$fracsin xx$$ does get closer and closer to $0$ when $x$ increases. In fact,
$$left|fracsin xxright|lefrac1x$$ and the RHS clearly tends to $0$.
"... isn't the asymptote something that a graph will touch and stay on ...": no, quite often an asymptote doesn't touch the curve. It just needs to come arbitrarily close. In the case at hand, it crosses it infinitely often, but this does not matter.
There are several misconceptions in your post.
$$fracsin xx$$ does get closer and closer to $0$ when $x$ increases. In fact,
$$left|fracsin xxright|lefrac1x$$ and the RHS clearly tends to $0$.
"... isn't the asymptote something that a graph will touch and stay on ...": no, quite often an asymptote doesn't touch the curve. It just needs to come arbitrarily close. In the case at hand, it crosses it infinitely often, but this does not matter.
edited Jul 23 at 15:52
answered Jul 23 at 14:48
Yves Daoust
111k665203
111k665203
add a comment |Â
add a comment |Â
up vote
4
down vote
I have already written to you about this. Look at the graph of your function:
Don't you agree that, as we move to the right, the graph gets closer to $0$? To be more precise, if we fix a number $varepsilon>0$, then, if $M$ is large enough, the graph of the restriction of $f$ to $[M,+infty)$ is between the lines $y=varepsilon$ and $y=-varepsilon$. That's what it means that the line $y=0$ is an asymptote of the graph of $f$.
add a comment |Â
up vote
4
down vote
I have already written to you about this. Look at the graph of your function:
Don't you agree that, as we move to the right, the graph gets closer to $0$? To be more precise, if we fix a number $varepsilon>0$, then, if $M$ is large enough, the graph of the restriction of $f$ to $[M,+infty)$ is between the lines $y=varepsilon$ and $y=-varepsilon$. That's what it means that the line $y=0$ is an asymptote of the graph of $f$.
add a comment |Â
up vote
4
down vote
up vote
4
down vote
I have already written to you about this. Look at the graph of your function:
Don't you agree that, as we move to the right, the graph gets closer to $0$? To be more precise, if we fix a number $varepsilon>0$, then, if $M$ is large enough, the graph of the restriction of $f$ to $[M,+infty)$ is between the lines $y=varepsilon$ and $y=-varepsilon$. That's what it means that the line $y=0$ is an asymptote of the graph of $f$.
I have already written to you about this. Look at the graph of your function:
Don't you agree that, as we move to the right, the graph gets closer to $0$? To be more precise, if we fix a number $varepsilon>0$, then, if $M$ is large enough, the graph of the restriction of $f$ to $[M,+infty)$ is between the lines $y=varepsilon$ and $y=-varepsilon$. That's what it means that the line $y=0$ is an asymptote of the graph of $f$.
answered Jul 23 at 14:45


José Carlos Santos
113k1698176
113k1698176
add a comment |Â
add a comment |Â
up vote
2
down vote
The definition of an horizontal asymptote is that
$$limlimits_x to infty f(x) = c.$$
Which is exactly the case here with $c=0$.
In no way the definition of an asymptote implies that the function is supposed to stay on the same side of the asymptote for $x$ large enough.
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
add a comment |Â
up vote
2
down vote
The definition of an horizontal asymptote is that
$$limlimits_x to infty f(x) = c.$$
Which is exactly the case here with $c=0$.
In no way the definition of an asymptote implies that the function is supposed to stay on the same side of the asymptote for $x$ large enough.
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
add a comment |Â
up vote
2
down vote
up vote
2
down vote
The definition of an horizontal asymptote is that
$$limlimits_x to infty f(x) = c.$$
Which is exactly the case here with $c=0$.
In no way the definition of an asymptote implies that the function is supposed to stay on the same side of the asymptote for $x$ large enough.
The definition of an horizontal asymptote is that
$$limlimits_x to infty f(x) = c.$$
Which is exactly the case here with $c=0$.
In no way the definition of an asymptote implies that the function is supposed to stay on the same side of the asymptote for $x$ large enough.
edited Jul 23 at 14:39
answered Jul 23 at 14:35


mathcounterexamples.net
23.9k21653
23.9k21653
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
add a comment |Â
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
So when x gets to infinity $sin(x)/x$ becomes 0? How so? Can you please explain this in the terms of someone who hasn't learnt calculus yet? Thanks.
– Ethan Chan
Jul 23 at 14:39
2
2
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Using simple words: $sin x$ is bounded by $1$. If you divide $1$ by a large number you get a number close to $0$.
– mathcounterexamples.net
Jul 23 at 14:40
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
Ah right, I forgot about that. But how do we know sinx will output 1 when x=infinity?
– Ethan Chan
Jul 23 at 14:47
1
1
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
It will not output $1$... It will output something that is less or equal to $1$ which is even better!
– mathcounterexamples.net
Jul 23 at 14:52
add a comment |Â
up vote
1
down vote
f(x)=sinx/x, the size of x has no effect on the graph's proximity to the asymptote.
Yes it does:
$$textmax_x>x_0left|fracsin(x)x-0right|leq frac1x_0$$
add a comment |Â
up vote
1
down vote
f(x)=sinx/x, the size of x has no effect on the graph's proximity to the asymptote.
Yes it does:
$$textmax_x>x_0left|fracsin(x)x-0right|leq frac1x_0$$
add a comment |Â
up vote
1
down vote
up vote
1
down vote
f(x)=sinx/x, the size of x has no effect on the graph's proximity to the asymptote.
Yes it does:
$$textmax_x>x_0left|fracsin(x)x-0right|leq frac1x_0$$
f(x)=sinx/x, the size of x has no effect on the graph's proximity to the asymptote.
Yes it does:
$$textmax_x>x_0left|fracsin(x)x-0right|leq frac1x_0$$
answered Jul 23 at 14:37
Wouter
5,50021434
5,50021434
add a comment |Â
add a comment |Â
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1
Here's a MathJax tutorial :)
– Shaun
Jul 23 at 14:33
1
"asymptote" simply means a line such that the distance between the line and the graph tends to zero. We don't care about fluctuations.
– Wojowu
Jul 23 at 14:34
4
"The size of x has no effect on the graph's proximity to the asymptote." Not so.
– saulspatz
Jul 23 at 14:36
1
@Wojowu According to Wikipedia (en.wikipedia.org/wiki/Asymptote), "Some sources include the requirement [in the definition of "asymptote"] that the curve may not cross the line infinitely often, but this is unusual for modern authors." A literal reading of the word's etymology would also support this requirement, so Ethan Chen is more justified than he might think. (In the context of rational functions, of course, the extra stipulation makes no difference.)
– Connor Harris
Jul 23 at 14:38