The vector field is perpendicular to the family of level surfaces












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The vector field given by $F(x,y,z)=leftlangle-x,-y,-z rightrangle $ is perpendicular to the family of level surfaces is composed of



$(1)$ spheres



$(2)$ ellipsoid,



$(3)$ planes,



$(4)$ None of the above.



Answer:



The option $(3)$ is true.



Am I right?



Help me










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    0












    $begingroup$


    The vector field given by $F(x,y,z)=leftlangle-x,-y,-z rightrangle $ is perpendicular to the family of level surfaces is composed of



    $(1)$ spheres



    $(2)$ ellipsoid,



    $(3)$ planes,



    $(4)$ None of the above.



    Answer:



    The option $(3)$ is true.



    Am I right?



    Help me










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      The vector field given by $F(x,y,z)=leftlangle-x,-y,-z rightrangle $ is perpendicular to the family of level surfaces is composed of



      $(1)$ spheres



      $(2)$ ellipsoid,



      $(3)$ planes,



      $(4)$ None of the above.



      Answer:



      The option $(3)$ is true.



      Am I right?



      Help me










      share|cite|improve this question











      $endgroup$




      The vector field given by $F(x,y,z)=leftlangle-x,-y,-z rightrangle $ is perpendicular to the family of level surfaces is composed of



      $(1)$ spheres



      $(2)$ ellipsoid,



      $(3)$ planes,



      $(4)$ None of the above.



      Answer:



      The option $(3)$ is true.



      Am I right?



      Help me







      calculus






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Dec 14 '18 at 7:57







      arifamath

















      asked Dec 14 '18 at 0:43









      arifamatharifamath

      1176




      1176






















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          $begingroup$

          The result is:




          The gradient of $f = f(x, y, z)$ is perpendicular to the level curves of $f$.




          In your case you know the gradient ${bf F}(x, y, z) = -(x, y, z) = -{bf r}$, where ${bf r}$ is the radial vector. So the question becomes: what is the surface to which the radial vector is perpendicular everywhere? And the solution is a sphere. In other words, the function level curves of $f$ are spheres centered at the origin.



          Note that in you post you calculate the divergence of ${bf}$: ${bf nabla} cdot {bf F} = -3$, but that doesn't have any particular meaning in this problem.






          share|cite|improve this answer









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            1 Answer
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            1












            $begingroup$

            The result is:




            The gradient of $f = f(x, y, z)$ is perpendicular to the level curves of $f$.




            In your case you know the gradient ${bf F}(x, y, z) = -(x, y, z) = -{bf r}$, where ${bf r}$ is the radial vector. So the question becomes: what is the surface to which the radial vector is perpendicular everywhere? And the solution is a sphere. In other words, the function level curves of $f$ are spheres centered at the origin.



            Note that in you post you calculate the divergence of ${bf}$: ${bf nabla} cdot {bf F} = -3$, but that doesn't have any particular meaning in this problem.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              The result is:




              The gradient of $f = f(x, y, z)$ is perpendicular to the level curves of $f$.




              In your case you know the gradient ${bf F}(x, y, z) = -(x, y, z) = -{bf r}$, where ${bf r}$ is the radial vector. So the question becomes: what is the surface to which the radial vector is perpendicular everywhere? And the solution is a sphere. In other words, the function level curves of $f$ are spheres centered at the origin.



              Note that in you post you calculate the divergence of ${bf}$: ${bf nabla} cdot {bf F} = -3$, but that doesn't have any particular meaning in this problem.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                The result is:




                The gradient of $f = f(x, y, z)$ is perpendicular to the level curves of $f$.




                In your case you know the gradient ${bf F}(x, y, z) = -(x, y, z) = -{bf r}$, where ${bf r}$ is the radial vector. So the question becomes: what is the surface to which the radial vector is perpendicular everywhere? And the solution is a sphere. In other words, the function level curves of $f$ are spheres centered at the origin.



                Note that in you post you calculate the divergence of ${bf}$: ${bf nabla} cdot {bf F} = -3$, but that doesn't have any particular meaning in this problem.






                share|cite|improve this answer









                $endgroup$



                The result is:




                The gradient of $f = f(x, y, z)$ is perpendicular to the level curves of $f$.




                In your case you know the gradient ${bf F}(x, y, z) = -(x, y, z) = -{bf r}$, where ${bf r}$ is the radial vector. So the question becomes: what is the surface to which the radial vector is perpendicular everywhere? And the solution is a sphere. In other words, the function level curves of $f$ are spheres centered at the origin.



                Note that in you post you calculate the divergence of ${bf}$: ${bf nabla} cdot {bf F} = -3$, but that doesn't have any particular meaning in this problem.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 14 '18 at 1:57









                caveraccaverac

                14.6k31130




                14.6k31130






























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