$((p-1)/2)!^2$ congruent $-(-1)^{(p-1)/2} mod p$how to solve $ax+by=c mod p$?Differences Between Multiples of...

Why is there an extra space when I type "ls" on the Desktop?

How to write a chaotic neutral protagonist and prevent my readers from thinking they are evil?

An Undercover Army

Why does this boat have a landing pad? (SpaceX's GO Searcher) Any plans for propulsive capsule landings?

What is the purpose of a disclaimer like "this is not legal advice"?

Is there a logarithm base for which the logarithm becomes an identity function?

Should I apply for my boss's promotion?

Too soon for a plot twist?

Precision notation for voltmeters

How spaceships determine each other's mass in space?

3.5% Interest Student Loan or use all of my savings on Tuition?

Is it a Cyclops number? "Nobody" knows!

Are small insurances worth it?

“I had a flat in the centre of town, but I didn’t like living there, so …”

What is the orbit and expected lifetime of Crew Dragon trunk?

How to make sure I'm assertive enough in contact with subordinates?

A running toilet that stops itself

Are brahmins allowed to drink alcohol?

Does an unused member variable take up memory?

Giving a career talk in my old university, how prominently should I tell students my salary?

Limpar string com Regex

When Central Limit Theorem breaks down

Insult for someone who "doesn't know anything"

Can the Witch Sight warlock invocation see through the Mirror Image spell?



$((p-1)/2)!^2$ congruent $-(-1)^{(p-1)/2} mod p$


how to solve $ax+by=c mod p$?Differences Between Multiples of Consecutive Odd PrimesProve or disprove: For every integer a, if a is not congruent to 0 (mod 3), the a^2 is congruent to 1 (mod 3)Prove that there is no perfect square that is congruent to 2 mod 10 and 3 mod 10.How to prove that $(a-b) mod N = a mod N + ((-b) mod N)$?What is a modular inverse?Ian Stewart difference between two real numbers with the same decimal expansion to n placesFind the smallest positive integer for which x mod 3 = 2 and x mod 4 = 3If a = b (mod m) and gcd(a,b) = 1, then gcd(a,m) = 1Efficient way to solve $31^6 mod 189$ without using any external devices.













1












$begingroup$


I have run across a similar question in several places and the difference between the similar question and my question is that there is a negative sign next to $(-1)^{(p-1)/2}$. I am trying to figure out how the proof of these two differ.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Wilson's theorem?
    $endgroup$
    – Lord Shark the Unknown
    yesterday










  • $begingroup$
    Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Also if anyone could upvote my question so I can actually comment on other posts that would be great
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Did you want the factorial symbol outside the parentheses in the title?
    $endgroup$
    – J. W. Tanner
    yesterday










  • $begingroup$
    Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
    $endgroup$
    – Bill Dubuque
    yesterday


















1












$begingroup$


I have run across a similar question in several places and the difference between the similar question and my question is that there is a negative sign next to $(-1)^{(p-1)/2}$. I am trying to figure out how the proof of these two differ.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Wilson's theorem?
    $endgroup$
    – Lord Shark the Unknown
    yesterday










  • $begingroup$
    Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Also if anyone could upvote my question so I can actually comment on other posts that would be great
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Did you want the factorial symbol outside the parentheses in the title?
    $endgroup$
    – J. W. Tanner
    yesterday










  • $begingroup$
    Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
    $endgroup$
    – Bill Dubuque
    yesterday
















1












1








1





$begingroup$


I have run across a similar question in several places and the difference between the similar question and my question is that there is a negative sign next to $(-1)^{(p-1)/2}$. I am trying to figure out how the proof of these two differ.










share|cite|improve this question











$endgroup$




I have run across a similar question in several places and the difference between the similar question and my question is that there is a negative sign next to $(-1)^{(p-1)/2}$. I am trying to figure out how the proof of these two differ.







elementary-number-theory modular-arithmetic






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited yesterday







redneckmathematician

















asked yesterday









redneckmathematicianredneckmathematician

124




124












  • $begingroup$
    Wilson's theorem?
    $endgroup$
    – Lord Shark the Unknown
    yesterday










  • $begingroup$
    Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Also if anyone could upvote my question so I can actually comment on other posts that would be great
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Did you want the factorial symbol outside the parentheses in the title?
    $endgroup$
    – J. W. Tanner
    yesterday










  • $begingroup$
    Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
    $endgroup$
    – Bill Dubuque
    yesterday




















  • $begingroup$
    Wilson's theorem?
    $endgroup$
    – Lord Shark the Unknown
    yesterday










  • $begingroup$
    Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Also if anyone could upvote my question so I can actually comment on other posts that would be great
    $endgroup$
    – redneckmathematician
    yesterday










  • $begingroup$
    Did you want the factorial symbol outside the parentheses in the title?
    $endgroup$
    – J. W. Tanner
    yesterday










  • $begingroup$
    Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
    $endgroup$
    – Bill Dubuque
    yesterday


















$begingroup$
Wilson's theorem?
$endgroup$
– Lord Shark the Unknown
yesterday




$begingroup$
Wilson's theorem?
$endgroup$
– Lord Shark the Unknown
yesterday












$begingroup$
Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
$endgroup$
– redneckmathematician
yesterday




$begingroup$
Yes you can use Wilsons to get it down to -1 congruent (-1)^((p-1)/2)((p-1)/2)!^2 mod p but I am unsure how to get to final answer from there.
$endgroup$
– redneckmathematician
yesterday












$begingroup$
Also if anyone could upvote my question so I can actually comment on other posts that would be great
$endgroup$
– redneckmathematician
yesterday




$begingroup$
Also if anyone could upvote my question so I can actually comment on other posts that would be great
$endgroup$
– redneckmathematician
yesterday












$begingroup$
Did you want the factorial symbol outside the parentheses in the title?
$endgroup$
– J. W. Tanner
yesterday




$begingroup$
Did you want the factorial symbol outside the parentheses in the title?
$endgroup$
– J. W. Tanner
yesterday












$begingroup$
Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
$endgroup$
– Bill Dubuque
yesterday






$begingroup$
Hint $, $ If $,a^{large 2}equiv 1,$ then $ axequiv {-}1 iff xequiv -a $ (by multiplying by $a). $ OP has $, aequiv (-1)^{large (p-1)/2}pmod{!p}$
$endgroup$
– Bill Dubuque
yesterday












1 Answer
1






active

oldest

votes


















0












$begingroup$

You said in the comments you use Wilson's theorem to show $$-1 equiv (-1)^{left(p-1right)/2}(frac {p-1} 2)!^2 pmod p,$$ and you want to show $$ -(-1)^{(p-1)/2}equivleft(frac {p-1} 2 right)!^2pmod p; ?$$



Multiply both sides by $(-1)^{(p-1)/2}$



and note that $ (-1)^{(p-1)/2} (-1)^{(p-1)/2}=(-1)^{p-1} = 1$ when $p$ is odd.






share|cite|improve this answer









$endgroup$













    Your Answer





    StackExchange.ifUsing("editor", function () {
    return StackExchange.using("mathjaxEditing", function () {
    StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
    StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
    });
    });
    }, "mathjax-editing");

    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%2f3139364%2fp-1-22-congruent-1p-1-2-mod-p%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    0












    $begingroup$

    You said in the comments you use Wilson's theorem to show $$-1 equiv (-1)^{left(p-1right)/2}(frac {p-1} 2)!^2 pmod p,$$ and you want to show $$ -(-1)^{(p-1)/2}equivleft(frac {p-1} 2 right)!^2pmod p; ?$$



    Multiply both sides by $(-1)^{(p-1)/2}$



    and note that $ (-1)^{(p-1)/2} (-1)^{(p-1)/2}=(-1)^{p-1} = 1$ when $p$ is odd.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      You said in the comments you use Wilson's theorem to show $$-1 equiv (-1)^{left(p-1right)/2}(frac {p-1} 2)!^2 pmod p,$$ and you want to show $$ -(-1)^{(p-1)/2}equivleft(frac {p-1} 2 right)!^2pmod p; ?$$



      Multiply both sides by $(-1)^{(p-1)/2}$



      and note that $ (-1)^{(p-1)/2} (-1)^{(p-1)/2}=(-1)^{p-1} = 1$ when $p$ is odd.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        You said in the comments you use Wilson's theorem to show $$-1 equiv (-1)^{left(p-1right)/2}(frac {p-1} 2)!^2 pmod p,$$ and you want to show $$ -(-1)^{(p-1)/2}equivleft(frac {p-1} 2 right)!^2pmod p; ?$$



        Multiply both sides by $(-1)^{(p-1)/2}$



        and note that $ (-1)^{(p-1)/2} (-1)^{(p-1)/2}=(-1)^{p-1} = 1$ when $p$ is odd.






        share|cite|improve this answer









        $endgroup$



        You said in the comments you use Wilson's theorem to show $$-1 equiv (-1)^{left(p-1right)/2}(frac {p-1} 2)!^2 pmod p,$$ and you want to show $$ -(-1)^{(p-1)/2}equivleft(frac {p-1} 2 right)!^2pmod p; ?$$



        Multiply both sides by $(-1)^{(p-1)/2}$



        and note that $ (-1)^{(p-1)/2} (-1)^{(p-1)/2}=(-1)^{p-1} = 1$ when $p$ is odd.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered yesterday









        J. W. TannerJ. W. Tanner

        2,9271217




        2,9271217






























            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%2f3139364%2fp-1-22-congruent-1p-1-2-mod-p%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

            Nidaros erkebispedøme

            Birsay

            Where did Arya get these scars? Unicorn Meta Zoo #1: Why another podcast? Announcing the arrival of Valued Associate #679: Cesar Manara Favourite questions and answers from the 1st quarter of 2019Why did Arya refuse to end it?Has the pronunciation of Arya Stark's name changed?Has Arya forgiven people?Why did Arya Stark lose her vision?Why can Arya still use the faces?Has the Narrow Sea become narrower?Does Arya Stark know how to make poisons outside of the House of Black and White?Why did Nymeria leave Arya?Why did Arya not kill the Lannister soldiers she encountered in the Riverlands?What is the current canonical age of Sansa, Bran and Arya Stark?