Graph of a function - asymptotes properties












0














Is it possible that the graph of a function has vertical asymptote if $D_{f} = mathbb{R}$?



Also, is it possible that the graph of a function intersects its asymptote? (horizontal, slant or vertical)



The answer to both questions seems a straight-forward NO to me, but can someone help prove that? Thanks!










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  • Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
    – user247327
    Nov 24 at 12:57










  • How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
    – weno
    Nov 24 at 12:58










  • I did not say anything at all about f(x)= 1/x. Go back and read my post again.
    – user247327
    Nov 24 at 13:01










  • I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
    – weno
    Nov 24 at 13:03










  • What is your definition of "asymptote"?
    – user247327
    Nov 24 at 13:04
















0














Is it possible that the graph of a function has vertical asymptote if $D_{f} = mathbb{R}$?



Also, is it possible that the graph of a function intersects its asymptote? (horizontal, slant or vertical)



The answer to both questions seems a straight-forward NO to me, but can someone help prove that? Thanks!










share|cite|improve this question






















  • Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
    – user247327
    Nov 24 at 12:57










  • How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
    – weno
    Nov 24 at 12:58










  • I did not say anything at all about f(x)= 1/x. Go back and read my post again.
    – user247327
    Nov 24 at 13:01










  • I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
    – weno
    Nov 24 at 13:03










  • What is your definition of "asymptote"?
    – user247327
    Nov 24 at 13:04














0












0








0







Is it possible that the graph of a function has vertical asymptote if $D_{f} = mathbb{R}$?



Also, is it possible that the graph of a function intersects its asymptote? (horizontal, slant or vertical)



The answer to both questions seems a straight-forward NO to me, but can someone help prove that? Thanks!










share|cite|improve this question













Is it possible that the graph of a function has vertical asymptote if $D_{f} = mathbb{R}$?



Also, is it possible that the graph of a function intersects its asymptote? (horizontal, slant or vertical)



The answer to both questions seems a straight-forward NO to me, but can someone help prove that? Thanks!







limits graphing-functions






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 24 at 12:52









weno

817




817












  • Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
    – user247327
    Nov 24 at 12:57










  • How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
    – weno
    Nov 24 at 12:58










  • I did not say anything at all about f(x)= 1/x. Go back and read my post again.
    – user247327
    Nov 24 at 13:01










  • I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
    – weno
    Nov 24 at 13:03










  • What is your definition of "asymptote"?
    – user247327
    Nov 24 at 13:04


















  • Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
    – user247327
    Nov 24 at 12:57










  • How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
    – weno
    Nov 24 at 12:58










  • I did not say anything at all about f(x)= 1/x. Go back and read my post again.
    – user247327
    Nov 24 at 13:01










  • I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
    – weno
    Nov 24 at 13:03










  • What is your definition of "asymptote"?
    – user247327
    Nov 24 at 13:04
















Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
– user247327
Nov 24 at 12:57




Consider the function: f(x)= 1/x if x is not 0, f(0)= 1. That function has a vertical asymptote at x= 0 but is defined for x= 0.
– user247327
Nov 24 at 12:57












How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
– weno
Nov 24 at 12:58




How can f(x) = 1/x be defined for x = 0, if x=/=0, hence domain D = R{0}? I'm not sure I understand.
– weno
Nov 24 at 12:58












I did not say anything at all about f(x)= 1/x. Go back and read my post again.
– user247327
Nov 24 at 13:01




I did not say anything at all about f(x)= 1/x. Go back and read my post again.
– user247327
Nov 24 at 13:01












I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
– weno
Nov 24 at 13:03




I understand now. But since y = 1 for x = 0, how can there be an asymptote then?
– weno
Nov 24 at 13:03












What is your definition of "asymptote"?
– user247327
Nov 24 at 13:04




What is your definition of "asymptote"?
– user247327
Nov 24 at 13:04










1 Answer
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If a function is continuous on $mathbb{R},$ then doesn't have a vertical asymptote. If $f$ is not continuous, it can happen what explained in comments.



It is not possible that a graph of a function cuts its vertical asymptote. That would contradict the definition of the function.



For the second part, a quote from Wikipedia:




Asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.




The distance between the courbe and the asymptote (horizontal or oblique/slant) has to tend to $0$ with $xtoinfty,$ intersections are allowed.

As an example, consider $$f(x)=frac x2 + frac{cos x}{sqrt x}.$$ Since $limlimits_{xtoinfty} left(f(x)-frac x2 right)=0,$ the line $y=frac x2$ is an asymptote of the graph of $f$ (see figure). However, they cut, even infinitely times.



enter image description here






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    1 Answer
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    active

    oldest

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

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    active

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    votes









    0














    If a function is continuous on $mathbb{R},$ then doesn't have a vertical asymptote. If $f$ is not continuous, it can happen what explained in comments.



    It is not possible that a graph of a function cuts its vertical asymptote. That would contradict the definition of the function.



    For the second part, a quote from Wikipedia:




    Asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.




    The distance between the courbe and the asymptote (horizontal or oblique/slant) has to tend to $0$ with $xtoinfty,$ intersections are allowed.

    As an example, consider $$f(x)=frac x2 + frac{cos x}{sqrt x}.$$ Since $limlimits_{xtoinfty} left(f(x)-frac x2 right)=0,$ the line $y=frac x2$ is an asymptote of the graph of $f$ (see figure). However, they cut, even infinitely times.



    enter image description here






    share|cite|improve this answer


























      0














      If a function is continuous on $mathbb{R},$ then doesn't have a vertical asymptote. If $f$ is not continuous, it can happen what explained in comments.



      It is not possible that a graph of a function cuts its vertical asymptote. That would contradict the definition of the function.



      For the second part, a quote from Wikipedia:




      Asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.




      The distance between the courbe and the asymptote (horizontal or oblique/slant) has to tend to $0$ with $xtoinfty,$ intersections are allowed.

      As an example, consider $$f(x)=frac x2 + frac{cos x}{sqrt x}.$$ Since $limlimits_{xtoinfty} left(f(x)-frac x2 right)=0,$ the line $y=frac x2$ is an asymptote of the graph of $f$ (see figure). However, they cut, even infinitely times.



      enter image description here






      share|cite|improve this answer
























        0












        0








        0






        If a function is continuous on $mathbb{R},$ then doesn't have a vertical asymptote. If $f$ is not continuous, it can happen what explained in comments.



        It is not possible that a graph of a function cuts its vertical asymptote. That would contradict the definition of the function.



        For the second part, a quote from Wikipedia:




        Asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.




        The distance between the courbe and the asymptote (horizontal or oblique/slant) has to tend to $0$ with $xtoinfty,$ intersections are allowed.

        As an example, consider $$f(x)=frac x2 + frac{cos x}{sqrt x}.$$ Since $limlimits_{xtoinfty} left(f(x)-frac x2 right)=0,$ the line $y=frac x2$ is an asymptote of the graph of $f$ (see figure). However, they cut, even infinitely times.



        enter image description here






        share|cite|improve this answer












        If a function is continuous on $mathbb{R},$ then doesn't have a vertical asymptote. If $f$ is not continuous, it can happen what explained in comments.



        It is not possible that a graph of a function cuts its vertical asymptote. That would contradict the definition of the function.



        For the second part, a quote from Wikipedia:




        Asymptote of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the x or y coordinates tends to infinity.




        The distance between the courbe and the asymptote (horizontal or oblique/slant) has to tend to $0$ with $xtoinfty,$ intersections are allowed.

        As an example, consider $$f(x)=frac x2 + frac{cos x}{sqrt x}.$$ Since $limlimits_{xtoinfty} left(f(x)-frac x2 right)=0,$ the line $y=frac x2$ is an asymptote of the graph of $f$ (see figure). However, they cut, even infinitely times.



        enter image description here







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 25 at 10:12









        user376343

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        2,7882822






























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