How to derive this identityProving $ 2n choose n = 2^n frac 1 cdot 3 cdot 5 cdots (2n-1)n! $Spivak's Calculus (Chapter 2, Exercise 17)Help manipulating simple cubic equationHelp needed verifying a trigonometric identityHow to prove this identity (equality)?Does $L^2 = P^2$ implies that $L = P$?How much velocity can a canister of fuel give a spaceship?Why $e^kn^k<k^ke^frac n-k2^k$ whenever $n geq k^2 2^k ln 2 (1+o(1)) $?Is it possible to perform a computation to know if an object is at rest and its location given a force versus position diagram?How was this sum simplified to a ratio of Sinh functions?

What is a good class if we remove subclasses?

Symbol: Put a smile symbol under a plus

Boss asked a co-worker to assault me

Why does my purified Pokémon need to be healed?

What are those bumps on top of the Antonov-225?

Markov-chain sentence generator in Python

What can Amex do if I cancel their card after using the sign up bonus miles?

Do Reform Jews believe in a theistic God?

Who invented Monoid?

Why did Saruman lie?

crippling fear of hellfire &, damnation, please help?

If I animate and control a zombie, does it benefit from Undead Fortitude when it's reduced to 0 HP?

Is there any way to stop a user from creating executables and running them?

Create the least compressible picture

Are employers legally allowed to pay employees in goods and services equal to or greater than the minimum wage?

Simplification of numbers

How far did Gandalf and the Balrog drop from the bridge in Moria?

My cat is a houdini

How can I find an old paper when the usual methods fail?

What is the hottest thing in the universe?

How would timezones work on a planet 100 times the size of our Earth

Can renaming a method preserve encapsulation?

Why is Python 2.7 still the default Python version in Ubuntu?

How can God warn people of the upcoming rapture without disrupting society?



How to derive this identity


Proving $ 2n choose n = 2^n frac 1 cdot 3 cdot 5 cdots (2n-1)n! $Spivak's Calculus (Chapter 2, Exercise 17)Help manipulating simple cubic equationHelp needed verifying a trigonometric identityHow to prove this identity (equality)?Does $L^2 = P^2$ implies that $L = P$?How much velocity can a canister of fuel give a spaceship?Why $e^kn^k<k^ke^frac n-k2^k$ whenever $n geq k^2 2^k ln 2 (1+o(1)) $?Is it possible to perform a computation to know if an object is at rest and its location given a force versus position diagram?How was this sum simplified to a ratio of Sinh functions?






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








4












$begingroup$


$$ frac ab -x= frac c-xdb+left(fracb-dbright) left(fraca-cb-d - x right) $$
It is easy to check it by computing right hand side. It feels unnatural and a little magical. I could't derive it starting from LHS



This identity is used in the proof of Stolz Cesaro theorem (https://ru.m.wikipedia.org/wiki/Теорема_Штольца). It is in russian I understood with the help of google translate .










share|cite|improve this question











$endgroup$













  • $begingroup$
    If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
    $endgroup$
    – Martin R
    10 hours ago







  • 3




    $begingroup$
    There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
    $endgroup$
    – callculus
    10 hours ago










  • $begingroup$
    Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
    $endgroup$
    – steven gregory
    8 hours ago










  • $begingroup$
    @callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
    $endgroup$
    – Milan
    8 hours ago










  • $begingroup$
    Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
    $endgroup$
    – Somos
    7 hours ago


















4












$begingroup$


$$ frac ab -x= frac c-xdb+left(fracb-dbright) left(fraca-cb-d - x right) $$
It is easy to check it by computing right hand side. It feels unnatural and a little magical. I could't derive it starting from LHS



This identity is used in the proof of Stolz Cesaro theorem (https://ru.m.wikipedia.org/wiki/Теорема_Штольца). It is in russian I understood with the help of google translate .










share|cite|improve this question











$endgroup$













  • $begingroup$
    If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
    $endgroup$
    – Martin R
    10 hours ago







  • 3




    $begingroup$
    There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
    $endgroup$
    – callculus
    10 hours ago










  • $begingroup$
    Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
    $endgroup$
    – steven gregory
    8 hours ago










  • $begingroup$
    @callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
    $endgroup$
    – Milan
    8 hours ago










  • $begingroup$
    Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
    $endgroup$
    – Somos
    7 hours ago














4












4








4


1



$begingroup$


$$ frac ab -x= frac c-xdb+left(fracb-dbright) left(fraca-cb-d - x right) $$
It is easy to check it by computing right hand side. It feels unnatural and a little magical. I could't derive it starting from LHS



This identity is used in the proof of Stolz Cesaro theorem (https://ru.m.wikipedia.org/wiki/Теорема_Штольца). It is in russian I understood with the help of google translate .










share|cite|improve this question











$endgroup$




$$ frac ab -x= frac c-xdb+left(fracb-dbright) left(fraca-cb-d - x right) $$
It is easy to check it by computing right hand side. It feels unnatural and a little magical. I could't derive it starting from LHS



This identity is used in the proof of Stolz Cesaro theorem (https://ru.m.wikipedia.org/wiki/Теорема_Штольца). It is in russian I understood with the help of google translate .







algebra-precalculus






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited 7 hours ago







Milan

















asked 10 hours ago









MilanMilan

5371 gold badge5 silver badges15 bronze badges




5371 gold badge5 silver badges15 bronze badges














  • $begingroup$
    If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
    $endgroup$
    – Martin R
    10 hours ago







  • 3




    $begingroup$
    There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
    $endgroup$
    – callculus
    10 hours ago










  • $begingroup$
    Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
    $endgroup$
    – steven gregory
    8 hours ago










  • $begingroup$
    @callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
    $endgroup$
    – Milan
    8 hours ago










  • $begingroup$
    Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
    $endgroup$
    – Somos
    7 hours ago

















  • $begingroup$
    If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
    $endgroup$
    – Martin R
    10 hours ago







  • 3




    $begingroup$
    There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
    $endgroup$
    – callculus
    10 hours ago










  • $begingroup$
    Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
    $endgroup$
    – steven gregory
    8 hours ago










  • $begingroup$
    @callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
    $endgroup$
    – Milan
    8 hours ago










  • $begingroup$
    Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
    $endgroup$
    – Somos
    7 hours ago
















$begingroup$
If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
$endgroup$
– Martin R
10 hours ago





$begingroup$
If you know what you are aiming at then you can start by adding and subtracting $fracc-xdb$ ...
$endgroup$
– Martin R
10 hours ago





3




3




$begingroup$
There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
$endgroup$
– callculus
10 hours ago




$begingroup$
There is a reason why the LHS is transformed like this. $b$ and $d$ do not fall from the sky. It seems you have to read the proof again more carefully.
$endgroup$
– callculus
10 hours ago












$begingroup$
Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
$endgroup$
– steven gregory
8 hours ago




$begingroup$
Step by step reduce the LHS to the RHS. Turn that upside down and you derive the RHS to the LHS.
$endgroup$
– steven gregory
8 hours ago












$begingroup$
@callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
$endgroup$
– Milan
8 hours ago




$begingroup$
@callculus It is transformed like that so we can show it is less than epsilon. In the proof i have the identity does fall from the sky. If you have a more intuitive explenation please share .
$endgroup$
– Milan
8 hours ago












$begingroup$
Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
$endgroup$
– Somos
7 hours ago





$begingroup$
Do you have a reference for the proof? If so, please include the link in your question in order to make it self contained.
$endgroup$
– Somos
7 hours ago











3 Answers
3






active

oldest

votes


















4












$begingroup$

Consider the task of cooking up a straight line by combining two other straight lines.



Given a straight line $y=-x+a$

You want to represent this as a sum of two other straight lines.

Letting the slope of one line to $-m$ forces the slope of other line to $-(1-m)$.

You can get that by comparing like terms in :
$$colorred-x+a = colorblue-mx + c - m'x+c'$$
Also constant term is $a-c$.

So above equation becomes
$$colorred-x+a = colorblue-mx + c + (1-m)left(dfraca-c1-m-xright)$$



enter image description here



Replacing $m$ by $fracdb$ and $a$ by $fracab$ gives your eqn.






share|cite|improve this answer











$endgroup$










  • 1




    $begingroup$
    that's an interesting way to concretize and visualize why such a transformation (+1)
    $endgroup$
    – G Cab
    8 hours ago


















3












$begingroup$

Starting from the LHS



$$fracab-x$$



we can subtract and add $fracc-xdb$ to form



$$Big(fracab-xBig) - fracc-xdb + fracc-xdb$$



which rearranges to



$$fracc-xdb+Big(fracab-x-fracc-xdbBig)$$



or



$$fracc-xdb+Big(fraca-c+xdb-xBig)$$



which is equivalent to



$$fracc-xdb+Big(fraca-bx-c+dxbBig)$$



where $left(fracb-dbright) left(fraca-cb-d - x right) = Big(fraca-bx-c+dxbBig)$ and therefore we have the RHS



$$fracc-xdb+left(fracb-dbright) left(fraca-cb-d - x right)$$






share|cite|improve this answer









$endgroup$






















    0












    $begingroup$

    Let
    $$
    Z=:fracleft(c-xdright)b+left(fracb-dbright):left(fraca-cb-d:-:x:right):$$

    Let
    $$ K=fracleft(c-xdright)b$$
    Let
    $$ N=left(fracb-dbright):left(fraca-cb-d:-:x:right):$$



    $$Z=K+N$$



    We will rewrite $left(fraca-cb-d:-:x:right):$ as:



    $$left(fraca-cb-d:-:x:right):=left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):$$



    $$N:=left(fracb-dbright)left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):=left(fracb-dbright)left(fraca-c:-xleft(b-dright)b-d:right)$$



    $$N:=left(fraca-c:-xleft(b-dright)b:right)$$



    $$N:=left(fraca-c:-xb+xdb:right)$$



    Using $Z=K+N$ and substituting the last expression for $N$ we get:



    $$z:=fracleft(c-xdright)b+left(fraca-c:-xb+xdb:right) $$



    $$z:=left(fraca:-xbb:right)$$



    $$ z:=fraca:b-x$$






    share|cite|improve this answer











    $endgroup$

















      Your Answer








      StackExchange.ready(function()
      var channelOptions =
      tags: "".split(" "),
      id: "69"
      ;
      initTagRenderer("".split(" "), "".split(" "), channelOptions);

      StackExchange.using("externalEditor", function()
      // Have to fire editor after snippets, if snippets enabled
      if (StackExchange.settings.snippets.snippetsEnabled)
      StackExchange.using("snippets", function()
      createEditor();
      );

      else
      createEditor();

      );

      function createEditor()
      StackExchange.prepareEditor(
      heartbeatType: 'answer',
      autoActivateHeartbeat: false,
      convertImagesToLinks: true,
      noModals: true,
      showLowRepImageUploadWarning: true,
      reputationToPostImages: 10,
      bindNavPrevention: true,
      postfix: "",
      imageUploader:
      brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
      contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
      allowUrls: true
      ,
      noCode: true, onDemand: true,
      discardSelector: ".discard-answer"
      ,immediatelyShowMarkdownHelp:true
      );



      );













      draft saved

      draft discarded


















      StackExchange.ready(
      function ()
      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3322232%2fhow-to-derive-this-identity%23new-answer', 'question_page');

      );

      Post as a guest















      Required, but never shown

























      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      4












      $begingroup$

      Consider the task of cooking up a straight line by combining two other straight lines.



      Given a straight line $y=-x+a$

      You want to represent this as a sum of two other straight lines.

      Letting the slope of one line to $-m$ forces the slope of other line to $-(1-m)$.

      You can get that by comparing like terms in :
      $$colorred-x+a = colorblue-mx + c - m'x+c'$$
      Also constant term is $a-c$.

      So above equation becomes
      $$colorred-x+a = colorblue-mx + c + (1-m)left(dfraca-c1-m-xright)$$



      enter image description here



      Replacing $m$ by $fracdb$ and $a$ by $fracab$ gives your eqn.






      share|cite|improve this answer











      $endgroup$










      • 1




        $begingroup$
        that's an interesting way to concretize and visualize why such a transformation (+1)
        $endgroup$
        – G Cab
        8 hours ago















      4












      $begingroup$

      Consider the task of cooking up a straight line by combining two other straight lines.



      Given a straight line $y=-x+a$

      You want to represent this as a sum of two other straight lines.

      Letting the slope of one line to $-m$ forces the slope of other line to $-(1-m)$.

      You can get that by comparing like terms in :
      $$colorred-x+a = colorblue-mx + c - m'x+c'$$
      Also constant term is $a-c$.

      So above equation becomes
      $$colorred-x+a = colorblue-mx + c + (1-m)left(dfraca-c1-m-xright)$$



      enter image description here



      Replacing $m$ by $fracdb$ and $a$ by $fracab$ gives your eqn.






      share|cite|improve this answer











      $endgroup$










      • 1




        $begingroup$
        that's an interesting way to concretize and visualize why such a transformation (+1)
        $endgroup$
        – G Cab
        8 hours ago













      4












      4








      4





      $begingroup$

      Consider the task of cooking up a straight line by combining two other straight lines.



      Given a straight line $y=-x+a$

      You want to represent this as a sum of two other straight lines.

      Letting the slope of one line to $-m$ forces the slope of other line to $-(1-m)$.

      You can get that by comparing like terms in :
      $$colorred-x+a = colorblue-mx + c - m'x+c'$$
      Also constant term is $a-c$.

      So above equation becomes
      $$colorred-x+a = colorblue-mx + c + (1-m)left(dfraca-c1-m-xright)$$



      enter image description here



      Replacing $m$ by $fracdb$ and $a$ by $fracab$ gives your eqn.






      share|cite|improve this answer











      $endgroup$



      Consider the task of cooking up a straight line by combining two other straight lines.



      Given a straight line $y=-x+a$

      You want to represent this as a sum of two other straight lines.

      Letting the slope of one line to $-m$ forces the slope of other line to $-(1-m)$.

      You can get that by comparing like terms in :
      $$colorred-x+a = colorblue-mx + c - m'x+c'$$
      Also constant term is $a-c$.

      So above equation becomes
      $$colorred-x+a = colorblue-mx + c + (1-m)left(dfraca-c1-m-xright)$$



      enter image description here



      Replacing $m$ by $fracdb$ and $a$ by $fracab$ gives your eqn.







      share|cite|improve this answer














      share|cite|improve this answer



      share|cite|improve this answer








      edited 9 hours ago

























      answered 9 hours ago









      ganeshie8ganeshie8

      4,7391 gold badge11 silver badges19 bronze badges




      4,7391 gold badge11 silver badges19 bronze badges










      • 1




        $begingroup$
        that's an interesting way to concretize and visualize why such a transformation (+1)
        $endgroup$
        – G Cab
        8 hours ago












      • 1




        $begingroup$
        that's an interesting way to concretize and visualize why such a transformation (+1)
        $endgroup$
        – G Cab
        8 hours ago







      1




      1




      $begingroup$
      that's an interesting way to concretize and visualize why such a transformation (+1)
      $endgroup$
      – G Cab
      8 hours ago




      $begingroup$
      that's an interesting way to concretize and visualize why such a transformation (+1)
      $endgroup$
      – G Cab
      8 hours ago













      3












      $begingroup$

      Starting from the LHS



      $$fracab-x$$



      we can subtract and add $fracc-xdb$ to form



      $$Big(fracab-xBig) - fracc-xdb + fracc-xdb$$



      which rearranges to



      $$fracc-xdb+Big(fracab-x-fracc-xdbBig)$$



      or



      $$fracc-xdb+Big(fraca-c+xdb-xBig)$$



      which is equivalent to



      $$fracc-xdb+Big(fraca-bx-c+dxbBig)$$



      where $left(fracb-dbright) left(fraca-cb-d - x right) = Big(fraca-bx-c+dxbBig)$ and therefore we have the RHS



      $$fracc-xdb+left(fracb-dbright) left(fraca-cb-d - x right)$$






      share|cite|improve this answer









      $endgroup$



















        3












        $begingroup$

        Starting from the LHS



        $$fracab-x$$



        we can subtract and add $fracc-xdb$ to form



        $$Big(fracab-xBig) - fracc-xdb + fracc-xdb$$



        which rearranges to



        $$fracc-xdb+Big(fracab-x-fracc-xdbBig)$$



        or



        $$fracc-xdb+Big(fraca-c+xdb-xBig)$$



        which is equivalent to



        $$fracc-xdb+Big(fraca-bx-c+dxbBig)$$



        where $left(fracb-dbright) left(fraca-cb-d - x right) = Big(fraca-bx-c+dxbBig)$ and therefore we have the RHS



        $$fracc-xdb+left(fracb-dbright) left(fraca-cb-d - x right)$$






        share|cite|improve this answer









        $endgroup$

















          3












          3








          3





          $begingroup$

          Starting from the LHS



          $$fracab-x$$



          we can subtract and add $fracc-xdb$ to form



          $$Big(fracab-xBig) - fracc-xdb + fracc-xdb$$



          which rearranges to



          $$fracc-xdb+Big(fracab-x-fracc-xdbBig)$$



          or



          $$fracc-xdb+Big(fraca-c+xdb-xBig)$$



          which is equivalent to



          $$fracc-xdb+Big(fraca-bx-c+dxbBig)$$



          where $left(fracb-dbright) left(fraca-cb-d - x right) = Big(fraca-bx-c+dxbBig)$ and therefore we have the RHS



          $$fracc-xdb+left(fracb-dbright) left(fraca-cb-d - x right)$$






          share|cite|improve this answer









          $endgroup$



          Starting from the LHS



          $$fracab-x$$



          we can subtract and add $fracc-xdb$ to form



          $$Big(fracab-xBig) - fracc-xdb + fracc-xdb$$



          which rearranges to



          $$fracc-xdb+Big(fracab-x-fracc-xdbBig)$$



          or



          $$fracc-xdb+Big(fraca-c+xdb-xBig)$$



          which is equivalent to



          $$fracc-xdb+Big(fraca-bx-c+dxbBig)$$



          where $left(fracb-dbright) left(fraca-cb-d - x right) = Big(fraca-bx-c+dxbBig)$ and therefore we have the RHS



          $$fracc-xdb+left(fracb-dbright) left(fraca-cb-d - x right)$$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 8 hours ago









          Axion004Axion004

          1,4176 silver badges17 bronze badges




          1,4176 silver badges17 bronze badges
























              0












              $begingroup$

              Let
              $$
              Z=:fracleft(c-xdright)b+left(fracb-dbright):left(fraca-cb-d:-:x:right):$$

              Let
              $$ K=fracleft(c-xdright)b$$
              Let
              $$ N=left(fracb-dbright):left(fraca-cb-d:-:x:right):$$



              $$Z=K+N$$



              We will rewrite $left(fraca-cb-d:-:x:right):$ as:



              $$left(fraca-cb-d:-:x:right):=left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):$$



              $$N:=left(fracb-dbright)left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):=left(fracb-dbright)left(fraca-c:-xleft(b-dright)b-d:right)$$



              $$N:=left(fraca-c:-xleft(b-dright)b:right)$$



              $$N:=left(fraca-c:-xb+xdb:right)$$



              Using $Z=K+N$ and substituting the last expression for $N$ we get:



              $$z:=fracleft(c-xdright)b+left(fraca-c:-xb+xdb:right) $$



              $$z:=left(fraca:-xbb:right)$$



              $$ z:=fraca:b-x$$






              share|cite|improve this answer











              $endgroup$



















                0












                $begingroup$

                Let
                $$
                Z=:fracleft(c-xdright)b+left(fracb-dbright):left(fraca-cb-d:-:x:right):$$

                Let
                $$ K=fracleft(c-xdright)b$$
                Let
                $$ N=left(fracb-dbright):left(fraca-cb-d:-:x:right):$$



                $$Z=K+N$$



                We will rewrite $left(fraca-cb-d:-:x:right):$ as:



                $$left(fraca-cb-d:-:x:right):=left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):$$



                $$N:=left(fracb-dbright)left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):=left(fracb-dbright)left(fraca-c:-xleft(b-dright)b-d:right)$$



                $$N:=left(fraca-c:-xleft(b-dright)b:right)$$



                $$N:=left(fraca-c:-xb+xdb:right)$$



                Using $Z=K+N$ and substituting the last expression for $N$ we get:



                $$z:=fracleft(c-xdright)b+left(fraca-c:-xb+xdb:right) $$



                $$z:=left(fraca:-xbb:right)$$



                $$ z:=fraca:b-x$$






                share|cite|improve this answer











                $endgroup$

















                  0












                  0








                  0





                  $begingroup$

                  Let
                  $$
                  Z=:fracleft(c-xdright)b+left(fracb-dbright):left(fraca-cb-d:-:x:right):$$

                  Let
                  $$ K=fracleft(c-xdright)b$$
                  Let
                  $$ N=left(fracb-dbright):left(fraca-cb-d:-:x:right):$$



                  $$Z=K+N$$



                  We will rewrite $left(fraca-cb-d:-:x:right):$ as:



                  $$left(fraca-cb-d:-:x:right):=left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):$$



                  $$N:=left(fracb-dbright)left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):=left(fracb-dbright)left(fraca-c:-xleft(b-dright)b-d:right)$$



                  $$N:=left(fraca-c:-xleft(b-dright)b:right)$$



                  $$N:=left(fraca-c:-xb+xdb:right)$$



                  Using $Z=K+N$ and substituting the last expression for $N$ we get:



                  $$z:=fracleft(c-xdright)b+left(fraca-c:-xb+xdb:right) $$



                  $$z:=left(fraca:-xbb:right)$$



                  $$ z:=fraca:b-x$$






                  share|cite|improve this answer











                  $endgroup$



                  Let
                  $$
                  Z=:fracleft(c-xdright)b+left(fracb-dbright):left(fraca-cb-d:-:x:right):$$

                  Let
                  $$ K=fracleft(c-xdright)b$$
                  Let
                  $$ N=left(fracb-dbright):left(fraca-cb-d:-:x:right):$$



                  $$Z=K+N$$



                  We will rewrite $left(fraca-cb-d:-:x:right):$ as:



                  $$left(fraca-cb-d:-:x:right):=left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):$$



                  $$N:=left(fracb-dbright)left(fraca-cb-d:-:x:fracleft(b-dright)left(b-dright):right):=left(fracb-dbright)left(fraca-c:-xleft(b-dright)b-d:right)$$



                  $$N:=left(fraca-c:-xleft(b-dright)b:right)$$



                  $$N:=left(fraca-c:-xb+xdb:right)$$



                  Using $Z=K+N$ and substituting the last expression for $N$ we get:



                  $$z:=fracleft(c-xdright)b+left(fraca-c:-xb+xdb:right) $$



                  $$z:=left(fraca:-xbb:right)$$



                  $$ z:=fraca:b-x$$







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited 7 hours ago

























                  answered 9 hours ago









                  NoChanceNoChance

                  4,4782 gold badges13 silver badges22 bronze badges




                  4,4782 gold badges13 silver badges22 bronze badges






























                      draft saved

                      draft discarded
















































                      Thanks for contributing an answer to Mathematics Stack Exchange!


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid


                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.

                      Use MathJax to format equations. MathJax reference.


                      To learn more, see our tips on writing great answers.




                      draft saved


                      draft discarded














                      StackExchange.ready(
                      function ()
                      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3322232%2fhow-to-derive-this-identity%23new-answer', 'question_page');

                      );

                      Post as a guest















                      Required, but never shown





















































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown

































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown







                      Popular posts from this blog

                      ParseJSON using SSJSUsing AMPscript with SSJS ActivitiesHow to resubscribe a user in Marketing cloud using SSJS?Pulling Subscriber Status from Lists using SSJSRetrieving Emails using SSJSProblem in updating DE using SSJSUsing SSJS to send single email in Marketing CloudError adding EmailSendDefinition using SSJS

                      Кампала Садржај Географија Географија Историја Становништво Привреда Партнерски градови Референце Спољашње везе Мени за навигацију0°11′ СГШ; 32°20′ ИГД / 0.18° СГШ; 32.34° ИГД / 0.18; 32.340°11′ СГШ; 32°20′ ИГД / 0.18° СГШ; 32.34° ИГД / 0.18; 32.34МедијиПодациЗванични веб-сајту

                      19. јануар Садржај Догађаји Рођења Смрти Празници и дани сећања Види још Референце Мени за навигацијуу