{"id":817,"date":"2020-08-22T18:43:33","date_gmt":"2020-08-22T18:43:33","guid":{"rendered":"http:\/\/localhost\/?page_id=817"},"modified":"2020-08-25T22:28:21","modified_gmt":"2020-08-25T22:28:21","slug":"exercicios-4-2","status":"publish","type":"page","link":"http:\/\/localhost\/index.php\/ensino\/algebra-a\/exercicios-4-2\/","title":{"rendered":"Exerc\u00edcios 4"},"content":{"rendered":"

1. Seja $n$ um n\u00famero natural tal que $n$, $n+2$ e $n+4$ s\u00e3o primos. Mostre que $n=3$.<\/p>\n

2. Seja $A=\\{4n+1\\mid n\\in\\mathbb Z\\}$ e $B=\\{4n-1\\mid n\\in\\mathbb Z\\}$. Mostre que<\/p>\n

    \n
  1. se $a,b\\in A$, ent\u00e3o $ab\\in A$;<\/li>\n
  2. se $a\\in A$ e $b\\in B$, ent\u00e3o $ab\\in B$;<\/li>\n
  3. se $a,b\\in B$, ent\u00e3o $ab\\in A$.<\/li>\n<\/ol>\n

    3. Mostre que existem infinitos primos no conjunto $B$ do exerc\u00edcio anterior.
    \n[Dica: Use o racioc\u00ednio da demonstra\u00e7\u00e3o do teorema sobre a infinitude dos primos.]<\/p>\n

    4. Mostre que $\\sqrt 2$ n\u00e3o \u00e9 um n\u00famero racional.
    \n[Dica: Assuma que $\\sqrt 2=a\/b$ com $a,b\\in\\mathbb N$ e use o Teorema da Fatora\u00e7\u00e3o para obter uma contradi\u00e7\u00e3o.]<\/p>\n

    No seguinte exerc\u00edcio, precisamos do conceito de mmc (menor m\u00faltiplo comum) de dois n\u00fameros inteiros. Assuma que $a,b\\in\\mathbb Z\\setminus\\{0\\}$. Dizemos que um n\u00famero $m$ \u00e9 mmc de $a$ e $b$ se<\/p>\n

      \n
    1. $m\\geq 0$;<\/li>\n
    2. $a|m$ e $b|m$;<\/li>\n
    3. se $c\\in \\mathbb Z$ tal que $a|c$ e $b|c$, ent\u00e3o $m|c$.<\/li>\n<\/ol>\n

      5. Sejam $a$ e $b$ n\u00fameros naturais com $a,b\\geq 2$ e assuma que
      \n\\[
      \na=p_1^{\\alpha_1}\\cdots p_k^{\\alpha_k}\\quad\\mbox{e}\\quad\u00a0p_1^{\\beta_1}\\cdots p_k^{\\beta_k}
      \n\\]
      \nonde os $p_i$ s\u00e3o primos mutualmente distintos e $\\alpha_i,\\beta_i\\geq 0$. Mostre que<\/p>\n

        \n
      1. $\\mbox{mdc}(a,b)=\u00a0p_1^{\\min\\{\\alpha_1,\\beta_1\\}}\\cdots p_k^{\\min\\{\\alpha_k,\\beta_k\\}}$;<\/li>\n
      2. $\\mbox{mmc}(a,b)=\u00a0p_1^{\\max\\{\\alpha_1,\\beta_1\\}}\\cdots p_k^{\\max\\{\\alpha_k,\\beta_k\\}}$.<\/li>\n
      3. $\\mbox{mdc}(a,b)\\cdot \\mbox{mmc}(a,b)=a\\cdot b$.<\/li>\n<\/ol>\n

        6. Defina para $n\\in\\mathbb N$,
        \n\\[
        \n\\pi(n)=|\\{k\\in\\{2,\\ldots,n\\}\\mid k\\mbox{ \u00e9 primo}\\}|.
        \n\\]
        \nSabe-se pelo Teorema do N\u00famero Primo<\/a>\u00a0que
        \n\\[
        \n\\lim_{n\\to\\infty} \\pi(n)\/(n\/\\log n)=1.
        \n\\]
        \nEscreva um programa em uma linguagem computacional que consegue determinar o valor de $\\pi(n)$ para n\u00fameros grandes ($n\\geq 10^6$) e calcule os valores de\u00a0 $\\pi(n)\/(n\/\\log n)$ para alguns n\u00fameros $n$.<\/p>\n","protected":false},"excerpt":{"rendered":"

        1. Seja $n$ um n\u00famero natural tal que $n$, $n+2$ e $n+4$ s\u00e3o primos. Mostre que $n=3$. 2. Seja $A=\\{4n+1\\mid n\\in\\mathbb Z\\}$ e $B=\\{4n-1\\mid n\\in\\mathbb Z\\}$. Mostre que se $a,b\\in A$, ent\u00e3o $ab\\in A$; se $a\\in A$ e $b\\in B$, ent\u00e3o $ab\\in B$; se $a,b\\in B$, ent\u00e3o $ab\\in A$. 3. Mostre que existem infinitos primos … Continue reading Exerc\u00edcios 4<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":706,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/pages\/817"}],"collection":[{"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/comments?post=817"}],"version-history":[{"count":7,"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/pages\/817\/revisions"}],"predecessor-version":[{"id":830,"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/pages\/817\/revisions\/830"}],"up":[{"embeddable":true,"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/pages\/706"}],"wp:attachment":[{"href":"http:\/\/localhost\/index.php\/wp-json\/wp\/v2\/media?parent=817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}