Inequality between normed vectors The Next CEO of Stack OverflowProve that the norm of $E$ is generate by the inner product $langle x,y rangle =frac14left(||x+y|^2-||x-y||^2right)$Linearly independent vectors in normed vector spaceClosure of a subset of normed vector spaceInequality in normed space with normalizationConvergence of vectors in a normed vector space.Showing an Isometry between normed space.Normed vector space inequality $||x|^2 - |y|^2| le |x-y||x+y|$Open ball in a normed vector spaceCoset is open in a normed linear spaceThe span of a finite number of vectors in a normed vector space is closed

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Inequality between normed vectors



The Next CEO of Stack OverflowProve that the norm of $E$ is generate by the inner product $langle x,y rangle =frac14left(||x+y|^2-||x-y||^2right)$Linearly independent vectors in normed vector spaceClosure of a subset of normed vector spaceInequality in normed space with normalizationConvergence of vectors in a normed vector space.Showing an Isometry between normed space.Normed vector space inequality $||x|^2 - |y|^2| le |x-y||x+y|$Open ball in a normed vector spaceCoset is open in a normed linear spaceThe span of a finite number of vectors in a normed vector space is closed










0












$begingroup$



Let $x,y$ be two vectors of an normed vector space $E$. Prove that
$$left|fracxx-fracyright|leq2fracx$$




Any hint/help?










share|cite|improve this question











$endgroup$







  • 1




    $begingroup$
    Hint: do you know the triangle inequality?
    $endgroup$
    – Alex
    Mar 28 at 1:20










  • $begingroup$
    First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
    $endgroup$
    – amsmath
    Mar 28 at 1:28















0












$begingroup$



Let $x,y$ be two vectors of an normed vector space $E$. Prove that
$$left|fracxx-fracyright|leq2fracx$$




Any hint/help?










share|cite|improve this question











$endgroup$







  • 1




    $begingroup$
    Hint: do you know the triangle inequality?
    $endgroup$
    – Alex
    Mar 28 at 1:20










  • $begingroup$
    First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
    $endgroup$
    – amsmath
    Mar 28 at 1:28













0












0








0





$begingroup$



Let $x,y$ be two vectors of an normed vector space $E$. Prove that
$$left|fracxx-fracyright|leq2fracx$$




Any hint/help?










share|cite|improve this question











$endgroup$





Let $x,y$ be two vectors of an normed vector space $E$. Prove that
$$left|fracxx-fracyright|leq2fracx$$




Any hint/help?







real-analysis






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Mar 28 at 1:24









Brian

1,208116




1,208116










asked Mar 28 at 1:18









pin_rpin_r

156




156







  • 1




    $begingroup$
    Hint: do you know the triangle inequality?
    $endgroup$
    – Alex
    Mar 28 at 1:20










  • $begingroup$
    First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
    $endgroup$
    – amsmath
    Mar 28 at 1:28












  • 1




    $begingroup$
    Hint: do you know the triangle inequality?
    $endgroup$
    – Alex
    Mar 28 at 1:20










  • $begingroup$
    First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
    $endgroup$
    – amsmath
    Mar 28 at 1:28







1




1




$begingroup$
Hint: do you know the triangle inequality?
$endgroup$
– Alex
Mar 28 at 1:20




$begingroup$
Hint: do you know the triangle inequality?
$endgroup$
– Alex
Mar 28 at 1:20












$begingroup$
First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
$endgroup$
– amsmath
Mar 28 at 1:28




$begingroup$
First multiply the whole thing by $|x|$ to get an equivalent inequality. Then prove this inequality by inserting $-y+y$ and the usage of both the usual triangle inequality $|u+v|le|u|+|v|$ and the inverse one: $||u|-|v||le|u-v|$.
$endgroup$
– amsmath
Mar 28 at 1:28










1 Answer
1






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oldest

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2












$begingroup$

$|xover x-yover
|leq |xover x-yover x|+|yover x-yover |$



$|yover x-yover |$=



$|y||(-overx)||=|-overx|leq -overx.$






share|cite|improve this answer









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    1 Answer
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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2












    $begingroup$

    $|xover x-yover
    |leq |xover x-yover x|+|yover x-yover |$



    $|yover x-yover |$=



    $|y||(-overx)||=|-overx|leq -overx.$






    share|cite|improve this answer









    $endgroup$

















      2












      $begingroup$

      $|xover x-yover
      |leq |xover x-yover x|+|yover x-yover |$



      $|yover x-yover |$=



      $|y||(-overx)||=|-overx|leq -overx.$






      share|cite|improve this answer









      $endgroup$















        2












        2








        2





        $begingroup$

        $|xover x-yover
        |leq |xover x-yover x|+|yover x-yover |$



        $|yover x-yover |$=



        $|y||(-overx)||=|-overx|leq -overx.$






        share|cite|improve this answer









        $endgroup$



        $|xover x-yover
        |leq |xover x-yover x|+|yover x-yover |$



        $|yover x-yover |$=



        $|y||(-overx)||=|-overx|leq -overx.$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Mar 28 at 1:30









        Tsemo AristideTsemo Aristide

        60.1k11446




        60.1k11446



























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