Is this a typo in Section 1.8.1 Mathematics for Computer Science?How can I learn about proofs for computer science?How can I start to learn proof theory?Proving the existence of a proof without actually giving a proofProof by well ordering: Every positive integer greater than one can be factored as a product of primes.Gentzen and computer scienceElegant demonstration with minimum category theory knowledgeDifferent definitions of Natural Numbers and Proof by ContradictionProve $3^2n-5$ is a multiple of $4$Defining new symbols in a proof, when is this justified?Prove convergence rate to zero increases as n increases

Is this a typo in Section 1.8.1 Mathematics for Computer Science?

How much of a wave function must reside inside event horizon for it to be consumed by the black hole?

How can I wire a 9-position switch so that each position turns on one more LED than the one before?

Is there a better way to say "see someone's dreams"?

An array in a equation with curly braces in both sides

Injection into a proper class and choice without regularity

Can a stored procedure reference the database in which it is stored?

Check if a string is entirely made of the same substring

Can a Bard use the Spell Glyph option of the Glyph of Warding spell and cast a known spell into the glyph?

Does a large simulator bay have standard public address announcements?

Which big number is bigger?

Mistake in years of experience in resume?

What is the term for a person whose job is to place products on shelves in stores?

Why is the underscore command _ useful?

Why did Rep. Omar conclude her criticism of US troops with the phrase "NotTodaySatan"?

Negative Resistance

What is the most expensive material in the world that could be used to create Pun-Pun's lute?

How do I check if a string is entirely made of the same substring?

Nails holding drywall

Multiple options vs single option UI

Would the change in enthalpy (ΔH) for the dissolution of urea in water be positive or negative?

My admission is revoked after accepting the admission offer

What was Apollo 13's "Little Jolt" after MECO?

std::unique_ptr of base class holding reference of derived class does not show warning in gcc compiler while naked pointer shows it. Why?



Is this a typo in Section 1.8.1 Mathematics for Computer Science?


How can I learn about proofs for computer science?How can I start to learn proof theory?Proving the existence of a proof without actually giving a proofProof by well ordering: Every positive integer greater than one can be factored as a product of primes.Gentzen and computer scienceElegant demonstration with minimum category theory knowledgeDifferent definitions of Natural Numbers and Proof by ContradictionProve $3^2n-5$ is a multiple of $4$Defining new symbols in a proof, when is this justified?Prove convergence rate to zero increases as n increases













3












$begingroup$


enter image description here



Am I completely mistake or is it suppose to say $n^2$ is a multiple of 2 and therefore $n$ must be a multiple of 4?



This is from MIT's Mathematics for Computer Science










share|cite|improve this question









$endgroup$











  • $begingroup$
    Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
    $endgroup$
    – DanielWainfleet
    3 hours ago















3












$begingroup$


enter image description here



Am I completely mistake or is it suppose to say $n^2$ is a multiple of 2 and therefore $n$ must be a multiple of 4?



This is from MIT's Mathematics for Computer Science










share|cite|improve this question









$endgroup$











  • $begingroup$
    Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
    $endgroup$
    – DanielWainfleet
    3 hours ago













3












3








3





$begingroup$


enter image description here



Am I completely mistake or is it suppose to say $n^2$ is a multiple of 2 and therefore $n$ must be a multiple of 4?



This is from MIT's Mathematics for Computer Science










share|cite|improve this question









$endgroup$




enter image description here



Am I completely mistake or is it suppose to say $n^2$ is a multiple of 2 and therefore $n$ must be a multiple of 4?



This is from MIT's Mathematics for Computer Science







proof-explanation proof-theory






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked 4 hours ago









doctopusdoctopus

1413




1413











  • $begingroup$
    Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
    $endgroup$
    – DanielWainfleet
    3 hours ago
















  • $begingroup$
    Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
    $endgroup$
    – DanielWainfleet
    3 hours ago















$begingroup$
Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
$endgroup$
– DanielWainfleet
3 hours ago




$begingroup$
Generally: If $m,n$ are positive integers and $m^1/n$ is not an integer then $m^1/n$ is irrational. Proved by a similar method.
$endgroup$
– DanielWainfleet
3 hours ago










2 Answers
2






active

oldest

votes


















3












$begingroup$

No, it is correct. The point is that $2d^2=n^2$ implies $n^2$ is even, and only even numbers square to give an even number, so $n$ much be even, so $n^2$ is then actually a multiple of $4$.






share|cite|improve this answer









$endgroup$




















    2












    $begingroup$

    No. $6^2$ is a multiple of $2$ but $6$ is not a multiple of $4$. If $n=2k$ then for sure $n^2=4k^2$. So, MIT is right.






    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%2f3202666%2fis-this-a-typo-in-section-1-8-1-mathematics-for-computer-science%23new-answer', 'question_page');

      );

      Post as a guest















      Required, but never shown

























      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      3












      $begingroup$

      No, it is correct. The point is that $2d^2=n^2$ implies $n^2$ is even, and only even numbers square to give an even number, so $n$ much be even, so $n^2$ is then actually a multiple of $4$.






      share|cite|improve this answer









      $endgroup$

















        3












        $begingroup$

        No, it is correct. The point is that $2d^2=n^2$ implies $n^2$ is even, and only even numbers square to give an even number, so $n$ much be even, so $n^2$ is then actually a multiple of $4$.






        share|cite|improve this answer









        $endgroup$















          3












          3








          3





          $begingroup$

          No, it is correct. The point is that $2d^2=n^2$ implies $n^2$ is even, and only even numbers square to give an even number, so $n$ much be even, so $n^2$ is then actually a multiple of $4$.






          share|cite|improve this answer









          $endgroup$



          No, it is correct. The point is that $2d^2=n^2$ implies $n^2$ is even, and only even numbers square to give an even number, so $n$ much be even, so $n^2$ is then actually a multiple of $4$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 4 hours ago









          John DoeJohn Doe

          12.2k11341




          12.2k11341





















              2












              $begingroup$

              No. $6^2$ is a multiple of $2$ but $6$ is not a multiple of $4$. If $n=2k$ then for sure $n^2=4k^2$. So, MIT is right.






              share|cite|improve this answer









              $endgroup$

















                2












                $begingroup$

                No. $6^2$ is a multiple of $2$ but $6$ is not a multiple of $4$. If $n=2k$ then for sure $n^2=4k^2$. So, MIT is right.






                share|cite|improve this answer









                $endgroup$















                  2












                  2








                  2





                  $begingroup$

                  No. $6^2$ is a multiple of $2$ but $6$ is not a multiple of $4$. If $n=2k$ then for sure $n^2=4k^2$. So, MIT is right.






                  share|cite|improve this answer









                  $endgroup$



                  No. $6^2$ is a multiple of $2$ but $6$ is not a multiple of $4$. If $n=2k$ then for sure $n^2=4k^2$. So, MIT is right.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered 4 hours ago









                  RandallRandall

                  10.8k11431




                  10.8k11431



























                      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%2f3202666%2fis-this-a-typo-in-section-1-8-1-mathematics-for-computer-science%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

                      Can not update quote_id field of “quote_item” table magento 2Magento 2.1 - We can't remove the item. (Shopping Cart doesnt allow us to remove items before becomes empty)Add value for custom quote item attribute using REST apiREST API endpoint v1/carts/cartId/items always returns error messageCorrect way to save entries to databaseHow to remove all associated quote objects of a customer completelyMagento 2 - Save value from custom input field to quote_itemGet quote_item data using quote id and product id filter in Magento 2How to set additional data to quote_item table from controller in Magento 2?What is the purpose of additional_data column in quote_item table in magento2Set Custom Price to Quote item magento2 from controller

                      Magento 2 disable Secret Key on URL's from terminal The Next CEO of Stack OverflowMagento 2 Shortcut/GUI tool to perform commandline tasks for windowsIn menu add configuration linkMagento oAuth : Generating access token and access secretMagento 2 security key issue in Third-Party API redirect URIPublic actions in admin controllersHow to Disable Cache in Custom WidgetURL Key not changing in Magento 2Product URL Key gets deleted when importing custom options - Magento 2Problem with reindex terminalMagento 2 - bin/magento Commands not working in Cpanel Terminal

                      Aasi (pallopeli) Navigointivalikko