{"id":1466,"date":"2025-07-20T21:36:00","date_gmt":"2025-07-20T12:36:00","guid":{"rendered":"https:\/\/math-friend.com\/?p=1466"},"modified":"2025-08-01T09:56:07","modified_gmt":"2025-08-01T00:56:07","slug":"%e3%80%90%e7%ad%91%e6%b3%a2%e5%a4%a7%e5%ad%a6%e5%85%a5%e8%a9%a6%e3%80%91%e5%af%be%e6%95%b0%e3%81%ae%e4%b8%8d%e7%ad%89%e5%bc%8f%e3%81%a7%e4%b8%8e%e3%81%88%e3%82%89%e3%82%8c%e3%82%8b%e9%a0%98%e5%9f%9f","status":"publish","type":"post","link":"https:\/\/math-friend.com\/?p=1466","title":{"rendered":"\u3010\u7b51\u6ce2\u5927\u5b66\u5165\u8a66\u3011\u5bfe\u6570\u306e\u4e0d\u7b49\u5f0f\u3067\u4e0e\u3048\u3089\u308c\u308b\u9818\u57df\u306e\u9762\u7a4d(2024)"},"content":{"rendered":"\n<p>\u4eca\u56de\u306f\u3053\u3061\u3089\u306e\u554f\u984c\u3092\u89e3\u3044\u3066\u3044\u304d\u307e\u3059.<\/p>\n\n\n\n<p class=\"has-border -border02\">\u4ee5\u4e0b\u306e\u554f\u3044\u306b\u7b54\u3048\u3088.<br>(1) \\(x&gt;1\\), \\(y&gt;1\\)\u306e\u3068\u304d, <br>$$<br>\\log_x{y}+\\log_y{x}\\geq 2<br>$$\u3092\u793a\u305b.<br>(2) \u4ee5\u4e0b\u306e\u9023\u7acb\u4e0d\u7b49\u5f0f\u304c\u8868\u3059\u9818\u57df\u3092\u56f3\u793a\u305b\u3088.<br>$$<br>x&gt;1,\\,\\,y&gt;x\\,\\, \\log_x{y}+\\log_y{x}&lt;\\frac{5}{2}<br>$$<br>(3) (2)\u306e\u9818\u57df\u3067\u3055\u3089\u306b\\(x^2+y^2&lt;12\\)\u3082\u6e80\u305f\u3059\u9818\u57df\u306b\u5883\u754c\u7dda\u3092\u542b\u3081\u305f\u56f3\u5f62\u3092\\(D\\)\u3068\u3059\u308b. \\(D\\)\u306e\u9762\u7a4d\u3092\u6c42\u3081\u3088.<br><span style=\"text-align:right;display:block;\">(2024 \u7b51\u6ce2\u5927\u5b66 \u6587\u7cfb[2] \u7406\u7cfb[2])<\/span><\/p>\n\n\n\n<p>\u5bfe\u6570\u306e\u5165\u3063\u305f\u4e0d\u7b49\u5f0f, \u305d\u3057\u3066\u4e0d\u7b49\u5f0f\u304c\u5b9a\u3081\u308b\u9818\u57df\u306e\u9762\u7a4d\u306e\u554f\u984c\u3067\u3059. \u5bfe\u6570\u306f\u7b26\u53f7\u304c\u308f\u304b\u308a\u306b\u304f\u304f, \u4e0d\u7b49\u5f0f\u64cd\u4f5c\u306a\u3069\u3067\u9593\u9055\u3063\u3066\u3057\u307e\u3046\u3053\u3068\u304c\u591a\u3044\u306e\u3067, \u6ce8\u610f\u3057\u3066\u89e3\u304d\u307e\u3057\u3087\u3046. \u305d\u306e\u4e0a\u3067, \u7b26\u53f7\u3092\u78ba\u8a8d\u3057\u305f\u3053\u3068\u3092\u7b54\u6848\u306b\u66f8\u304b\u306a\u3044\u3068\u6e1b\u70b9\u5bfe\u8c61\u306b\u306a\u308b\u306e\u3067\u6c17\u3092\u3064\u3051\u307e\u3057\u3087\u3046.<br><br>\u307e\u305f, \u9762\u7a4d\u3092\u6c42\u3081\u308b\u9818\u57df\u306e\u4e00\u90e8\u306b\u5186\u304c\u5883\u754c\u3068\u3057\u3066\u73fe\u308c\u307e\u3059. \u6587\u7cfb\u306f\u30eb\u30fc\u30c8\u306e\u5165\u3063\u305f\u7a4d\u5206\u3092\u6271\u308f\u306a\u3044\u305f\u3081, \u76f4\u63a5\u7a4d\u5206\u3067\u6c42\u3081\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u305b\u3093. \u305d\u306e\u3053\u3068\u3092\u8003\u616e\u3057\u3066\u89e3\u7b54\u3092\u4f5c\u6210\u3057\u3066\u3044\u307e\u3059. \u89e3\u7b54\u5f8c\u306b\u5225\u89e3\u3067\u30eb\u30fc\u30c8\u306e\u5165\u3063\u305f\u7a4d\u5206\u3067\u9762\u7a4d\u3092\u6c42\u3081\u308b\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u3066\u3044\u307e\u3059.<br><br>\u305d\u308c\u3067\u306f\u89e3\u3044\u3066\u3044\u304d\u307e\u3057\u3087\u3046.<\/p>\n\n\n\n<div class=\"wp-block-group is-style-crease\"><div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<p>(1) \\(\\log_x{y}\\), \\(\\log_y{x}\\)\u306b\u3064\u3044\u3066, \\(x&gt;1\\), \\(y&gt;1\\)\u3067\u3042\u308b\u304b\u3089, \u3053\u308c\u3089\u306f\u3044\u305a\u308c\u3082\u6b63\u3067\u3042\u308b. \u3088\u3063\u3066, \u76f8\u52a0\u76f8\u4e57\u5e73\u5747\u304b\u3089,<br>$$<br>\\log_x{y}+\\log_y{x}\\geq 2\\sqrt{\\log_x{y} \\cdot \\log_y{x}}<br>$$\u3067\u3042\u308b. \u3053\u3053\u3067, \u5e95\u306e\u5909\u63db\u516c\u5f0f\u304b\u3089\\(\\log_y{x}\\)\u306e\u5e95\u3092\\(x\\)\u306b\u5909\u63db\u3059\u308b\u3068,<br>$$\\log_y{x}=\\frac{\\log_x{x}}{\\log_x{y}}=\\frac{1}{\\log_x{y}}<br>$$\u3067\u3042\u308b\u304b\u3089, <br>$$<br>\\log_x{y}+\\log_y{x}\\geq 2\\sqrt{\\log_x{y} \\cdot \\frac{1}{\\log_x{y}}}=2<br>$$\u304c\u308f\u304b\u308b. <br><br>\u7b49\u53f7\u6210\u7acb\u306f,<br>$$<br>\\log_x{y}=\\log_y{x}<br>$$\u3088\u308a, <br>$$<br>\\log_x{y}=\\frac{1}{\\log_x{y}}<br>\\iff \\left(\\log_x{y}\\right)^2=1<br>$$\u304c\u6210\u308a\u7acb\u3064\u3068\u304d\u3067\u3042\u308b. \\(\\log_x{y}&gt;0\\)\u3067\u3042\u308b\u304b\u3089, \u3053\u308c\u306f, \\(\\log_x{y}=1\\)\u3068\u540c\u5024\u3067\u3042\u308a, \u7d50\u679c, \\(x=y\\)\u306e\u3068\u304d\u3067\u3042\u308b\u3053\u3068\u304c\u308f\u304b\u308b. <\/p>\n\n\n\n<p>(2) \\(x>1\\), \\(y>x\\)\u3088\u308a, \\(\\log_x{y}>1\\)\u3067\u3042\u308b\u3053\u3068\u306b\u6ce8\u610f\u3057\u3066, \\(\\log_x{y}+\\log_y{x}&lt;\\frac{5}{2}\\)\u3092\u540c\u5024\u5909\u5f62\u3059\u308b\u3068, <br>$$<br>\\begin{align}<br>&amp; \\log_x{y}+\\log_y{x}&lt;\\frac{5}{2}\\\\[1.5ex]<br>\\iff &amp; \\log_x{y}+\\frac{1}{\\log_x{y}}&lt;\\frac{5}{2}\\\\[1.5ex]<br>\\iff &amp; 2\\left(\\log_x{y}\\right)^2-5\\log_x{y}+2&lt;0\\\\[1.5ex]<br>\\iff &amp; (2\\log_x{y}-1)(\\log_x{y}-2)&lt;0\\\\[1.5ex]<br>\\iff &amp; \\frac{1}{2}&lt;\\log_x{y}&lt;2\\\\[1.5ex]<br>\\iff &amp; 1&lt;\\log_x{y}&lt;2\\,\\,(\u524d\u63d0\u3067, \\log_x{y}>1 \u306e\u305f\u3081)<br>\\end{align}<br>$$\u3067\u3042\u308b. \u3053\u3053\u3067,\\(x>1\\)\u3088\u308a, \\(a&lt;b\\)\u306a\u3089\u3070\\(x^a&lt;x^b\\)\u3067\u3042\u308b\u304b\u3089, \u6700\u5f8c\u306e\u4e0d\u7b49\u5f0f\u3088\u308a, <br>$$<br>\\begin{align}<br>&amp; \\log_x{y}+\\log_y{x}&lt;\\frac{5}{2}\\\\[1.5ex]<br>\\iff &amp; 1&lt;\\log_x{y}&lt;2\\\\[1.5ex]<br>\\iff &amp; x^1&lt;x^{\\log_x{y}}&lt;x^2\\\\[1.5ex]<br>\\iff &amp; x&lt;y&lt;x^2<br>\\end{align}<br>$$\u3088\u3063\u3066, \\(x>1\\), \\(y>x\\)\u3068\u5408\u308f\u305b\u3066\u9818\u57df\u3092\u56f3\u793a\u3059\u308b\u3068, \u4ee5\u4e0b\u3068\u306a\u308b. \u305f\u3060\u3057, \u3044\u305a\u308c\u306e\u5883\u754c\u7dda\u3082\u542b\u307e\u306a\u3044.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" width=\"626\" height=\"617\" src=\"http:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/8ea1c8e85f21eb9b56f081e728adaa89.png\" alt=\"\" class=\"wp-image-1543\" style=\"width:429px;height:auto\" srcset=\"https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/8ea1c8e85f21eb9b56f081e728adaa89.png 626w, https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/8ea1c8e85f21eb9b56f081e728adaa89-300x296.png 300w\" sizes=\"(max-width: 626px) 100vw, 626px\" \/><\/figure>\n\n\n\n<p>(3) \\(x^2+y^2&lt;12\\)\u306e\u6761\u4ef6\u3092\u52a0\u3048\u9818\u57df\u3092\u56f3\u793a\u3059\u308b\u3068, \u4ee5\u4e0b\u306e\u901a\u308a\u3068\u306a\u308b. \u3053\u3053\u3067, \\(x^2+y^2&lt;12\\)\u306e\u5883\u754c\u3067\u3042\u308b\u5186\\(x^2+y^2=12\\)\u3068, \\(y=x^2\\), \\(y=x\\)\u306e\u7b2c\u4e00\u8c61\u9650\u306b\u304a\u3051\u308b\u4ea4\u70b9\u3092\u305d\u308c\u305e\u308c\\(\\mathrm{A}\\), \\(\\mathrm{B}\\)\u3068\u3057\u3066\u3044\u308b.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" width=\"600\" height=\"582\" src=\"http:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/1696419fc6974528e14ddbbb2e8e72a9.png\" alt=\"\" class=\"wp-image-1548\" style=\"width:436px;height:auto\" srcset=\"https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/1696419fc6974528e14ddbbb2e8e72a9.png 600w, https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/1696419fc6974528e14ddbbb2e8e72a9-300x291.png 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><\/figure>\n\n\n\n<p>\u3053\u3053\u3067\\(\\mathrm{O}\\)\u3068\\(\\mathrm{A}\\)\u3092\u76f4\u7dda\u3067\u7d50\u3073, \u6247\u5f62\\(\\mathrm{OAB}\\)\u3092\u8003\u3048\u308b. \u3053\u306e\u3068\u304d, \u4ee5\u4e0b\u306e\u56f3\u304b\u3089\u6c42\u3081\u308b\u9818\u57dfD\u306e\u5883\u754c\u7dda\u3092\u542b\u3081\u305f\u9762\u7a4d\\(S\\)\u306f,<br>$$<br>\\begin{align}<br>S&amp;= (\u6247\u5f62\\mathrm{OAB}\u306e\u9762\u7a4d)-(\u76f4\u7dda\\mathrm{OA}\u3068y=x^2\u3067\u56f2\u307e\u308c\u308b\u9818\u57df\u306e\u9762\u7a4d)\\\\<br>&amp;+(y=x\u3068y=x^2\u3067\u56f2\u307e\u308c\u308b\u9818\u57df\u306e\u9762\u7a4d)<br>\\end{align}<br>$$\u3068\u306a\u308b\u3053\u3068\u304c\u308f\u304b\u308b.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" width=\"932\" height=\"532\" src=\"http:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/6bd20e3dff4f7add264f28b5b5c54ea9.png\" alt=\"\" class=\"wp-image-1551\" style=\"width:568px;height:auto\" srcset=\"https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/6bd20e3dff4f7add264f28b5b5c54ea9.png 932w, https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/6bd20e3dff4f7add264f28b5b5c54ea9-300x171.png 300w, https:\/\/math-friend.com\/wp-content\/uploads\/2025\/07\/6bd20e3dff4f7add264f28b5b5c54ea9-768x438.png 768w\" sizes=\"(max-width: 932px) 100vw, 932px\" \/><\/figure>\n\n\n\n<p>\u307e\u305a\u6247\u5f62\\(\\mathrm{OAB}\\)\u306e\u9762\u7a4d\\(S_1\\)\u3092\u6c42\u3081\u308b\u305f\u3081\u306b, \\(\\mathrm{A}\\)\u306e\u5ea7\u6a19\u3092\u6c42\u3081\u308b. \u3053\u308c\u306f, \\(y=x^2\\)\u3068\\(x^2+y^2=12\\)\u3092\u9023\u7acb\u3057\u3066, \\(y\\)\u3092\u6d88\u53bb\u3059\u308b\u3053\u3068\u3067, <br>$$<br>\\begin{align}<br>&amp;x^2+\\left(x^2\\right)^2=12\\\\[1.5ex]<br>\\iff &amp;x^4+x^2-12=0\\\\[1.5ex]<br>\\iff &amp;(x^2+4)(x^2-3)=0\\\\[1.5ex]<br>\\iff &amp;x^2=3<br>\\end{align}<br>$$ \u3068\u306a\u308b. \u3053\u3053\u3067, \\(\\mathrm{A}\\)\u306f\u7b2c\u4e00\u8c61\u9650\u306b\u3042\u308b\u306e\u3067, \\(x=\\sqrt{3}\\)\u304c\u308f\u304b\u308a, \\(\\mathrm{A}\\)\u306e\u5ea7\u6a19\u306f\\((\\sqrt{3}, 3)\\)\u3067\u3042\u308b.<br><br>\u3053\u308c\u304b\u3089\u76f4\u7dda\\(\\mathrm{OA}\\)\u306e\u50be\u304d\u306f\\(\\displaystyle \\frac{3}{\\sqrt{3}}=\\sqrt{3}\\)\u3068\u306a\u308a, \u76f4\u7dda\\(\\mathrm{OA}\\)\u304c\\(x\\)\u8ef8\u306e\u6b63\u306e\u65b9\u5411\u3068\u306a\u3059\u89d2\u306e\u5927\u304d\u3055\u306f, \\(\\displaystyle \\frac{\\pi}{3}\\)\u3067\u3042\u308b\u3053\u3068\u304c\u308f\u304b\u308b. \u3055\u3089\u306b\u76f4\u7dda\\(y=x\\)\u304c\\(x\\)\u8ef8\u306e\u6b63\u306e\u65b9\u5411\u3068\u306a\u3059\u89d2\u306e\u5927\u304d\u3055\u306f, \\(\\displaystyle \\frac{\\pi}{4}\\)\u3067\u3042\u308b\u304b\u3089, \u6247\u5f62\\(\\mathrm{OAB}\\)\u306e\u4e2d\u5fc3\u89d2\u306e\u5927\u304d\u3055\\(\\angle{\\mathrm{OAB}}\\)\u306f, <br>$$<br>\\angle{\\mathrm{OAB}}=\\frac{\\pi}{3}-\\frac{\\pi}{4}=\\frac{\\pi}{12}<br>$$\u3068\u306a\u308b.<br><br>\u6247\u5f62\\(\\mathrm{OAB}\\)\u306f\u534a\u5f84\\(2\\sqrt{3}(=\\sqrt{12}\\))\u306e\u5186\u304b\u3089\u5207\u308a\u51fa\u3055\u308c\u305f\u3082\u306e\u306a\u306e\u3067, \u305d\u306e\u9762\u7a4d\\(S_1\\)\u306f,<br>$$<br>S_1 = \\pi(2\\sqrt{3})^2\\times\\frac{\\frac{\\pi}{12}}{2\\pi}=\\frac{\\pi}{2}<br>$$\u3068\u306a\u308b.<br><br>\u6b21\u306b, \u76f4\u7dda\\(\\mathrm{OA}(y=\\sqrt{3}x)\\)\u3068\\(y=x^2\\), \u76f4\u7dda\\(y=x\\)\u3068\\(y=x^2\\)\u306b\u56f2\u307e\u308c\u305f\u9818\u57df\u306e\u9762\u7a4d\\(S_2\\), \\(S_3\\)\u3092\u305d\u308c\u305e\u308c\u6c42\u3081\u308b. \u3053\u308c\u306f\u7a4d\u5206\u304b\u3089\u7c21\u5358\u306b\u6c42\u307e\u308a, <br>$$<br>\\begin{align}<br>S_2&amp;=\\int_0^{\\sqrt{3}}{\\sqrt{3}x-x^2}\\,dx=\\left[\\frac{\\sqrt{3}}{2}x^2-\\frac{1}{3}x^3\\right]_0^{\\sqrt{3}}\\\\[1.5ex]<br>&amp;=\\frac{3\\sqrt{3}}{2}-\\sqrt{3}=\\frac{\\sqrt{3}}{2}\\\\[1.5ex]<br>S_3&amp;=\\int_0^1{x-x^2}\\,dx=\\left[\\frac{\\sqrt{x^2}}{2}-\\frac{1}{3}x^3\\right]_0^1\\\\[1.5ex]<br>&amp;=\\frac{\\sqrt{1}}{2}-\\frac{1}{3}=\\frac{1}{6}<br>\\end{align}<br>$$\u3068\u306a\u308b. <br><br>\u3088\u3063\u3066\u6700\u7d42\u7684\u306b\u5883\u754c\u7dda\u3092\u542b\u3081\u305f\u9818\u57df\\(D\\)\u306e\u9762\u7a4d\\(S\\)\u306f, <br>$$<br>S=S_1-S_2+S_3=\\frac{\\pi}{2}-\\frac{\\sqrt{3}}{2}+\\frac{1}{6}<br>$$\u3068\u6c42\u307e\u308b.<\/p>\n<\/div><\/div>\n\n\n\n<p>\u5148\u306e\u89e3\u7b54\u306f\u30eb\u30fc\u30c8\u306e\u5165\u3063\u305f\u7a4d\u5206\u3092\u6271\u3046\u3053\u3068\u304c\u3067\u304d\u306a\u3044\u6587\u7cfb\u306e\u65b9\u5411\u3051\u306e\u89e3\u7b54\u3067\u3057\u305f. \u30eb\u30fc\u30c8\u304c\u5165\u3063\u305f\u7a4d\u5206\u3092\u4f7f\u3048\u306a\u3044\u3053\u3068\u304b\u3089, \u7a4d\u5206\u3067\u5186\u306e\u4e00\u90e8\u3068\u76f4\u7dda\u3067\u56f2\u307e\u308c\u308b\u9762\u7a4d\u3092\u6c42\u3081\u308b\u3053\u3068\u304c\u3067\u304d\u306a\u3044\u305f\u3081, \u65e2\u77e5\u306e\u5186\u3084\u6247\u5f62\u306e\u9762\u7a4d\u306e\u516c\u5f0f\u3092\u4f7f\u3063\u3066\\(D\\)\u306e\u9762\u7a4d\u3092\u6c42\u3081\u3066\u3044\u304d\u307e\u3057\u305f. \u3053\u306e\u767a\u60f3\u306f\u306a\u304b\u306a\u304b\u6c17\u3065\u304d\u306b\u304f\u304f\u96e3\u6613\u5ea6\u306e\u9ad8\u3044\u554f\u984c\u3067\u306f\u306a\u3044\u304b\u3068\u601d\u3063\u3066\u304a\u308a\u307e\u3059. <br><br>\u7406\u7cfb\u3067\u3042\u308c\u3070\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u7a4d\u5206\u3059\u308b\u3053\u3068\u3067\u7c21\u5358\u306b\u6c42\u3081\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059.<\/p>\n\n\n\n<p class=\"has-border -border03\">(3)\u306e\u5225\u89e3 (\u7406\u7cfb, \u304a\u3088\u3073\u30eb\u30fc\u30c8\u306e\u5165\u3063\u305f\u7a4d\u5206\u3092\u77e5\u3063\u3066\u3044\u308b\u6587\u7cfb\u5411\u3051)<br><br>\u307e\u305a, \\(\\mathrm{B}\\)\u306e\u5ea7\u6a19\u3092\u6c42\u3081\u308b. \u3053\u308c\u306f, \\(y=x\\)\u3068\\(x^2+y^2=12\\)\u3092\u9023\u7acb\u3057\u3066, \\(y\\)\u3092\u6d88\u53bb\u3059\u308b\u3053\u3068\u3067<br>$$<br>\\begin{align}<br>&amp;x^2+x^2=12\\\\[1.5ex]<br>&amp;\\iff x^2=6\\\\[1.5ex]<br>&amp;\\iff x=\\pm\\sqrt{6}<br>\\end{align}<br>$$\u3068\u306a\u308a, \\(\\mathrm{B}\\)\u306f\u7b2c\u4e00\u8c61\u9650\u306b\u3042\u308b\u306e\u3067, \\(x=\\sqrt{6}\\)\u3068\u306a\u308b. \u3053\u308c\u304b\u3089, \\(\\mathrm{B}\\)\u306e\u5ea7\u6a19\u306f\\((\\sqrt{6}, \\sqrt{6})\\)\u3067\u3042\u308b\u3053\u3068\u304c\u308f\u304b\u308b.<br><br>\u5186\\(x^2+y^2=12\\)\u306e\\(x\\)\u8ef8\u3088\u308a\u4e0a\u306e\u90e8\u5206\u306f\\(\\displaystyle y=\\sqrt{12-x^2}\\)\u3068\u8868\u305b\u308b\u306e\u3067, \u5883\u754c\u3092\u542b\u3081\u305f\u9818\u57df\\(D\\)\u9762\u7a4d\\(S\\)\u306f, <br>$$<br>\\begin{align}<br>S&amp;=\\int_1^\\sqrt{3}\\left(x^2-x\\right)\\,dx+\\int_\\sqrt{3}^\\sqrt{6}\\left(\\sqrt{12-x^2}-x\\right)\\,dx\\\\[1.5ex]<br>&amp;=\\int_1^\\sqrt{3}\\left(x^2-x\\right)\\,dx+\\int_\\sqrt{3}^\\sqrt{6}{\\sqrt{12-x^2}}\\,dx-\\int_\\sqrt{3}^\\sqrt{6}{x}\\,dx<br>\\end{align}<br>$$\u3092\u8a08\u7b97\u3059\u308c\u3070\u826f\u3044. \u7a4d\u5206\u3092\u305d\u308c\u305e\u308c\u8a08\u7b97\u3059\u308b.<br>1\u3064\u76ee\u306e\u7a4d\u5206\u306f,<br>$$<br>\\begin{align}<br>\\int_1^\\sqrt{3}\\left(x^2-x\\right)\\,dx&amp;=\\left[\\frac{\\sqrt{x^3}}{3}-\\frac{x^2}{2}\\right]_1^\\sqrt{3}\\\\[1.5ex]<br>&amp;=\\sqrt{3}-\\frac{3}{2}-\\frac{1}{3}+\\frac{1}{2}\\\\[1.5ex]<br>&amp;=\\sqrt{3}-\\frac{4}{3}<br>\\end{align}<br>$$\u3068\u8a08\u7b97\u3067\u304d\u308b.<br><br>2\u3064\u76ee\u306e\u7a4d\u5206\u306f, \\(x=2\\sqrt{3}\\sin{\\theta}\\)\u3068\u3057\u3066\u7f6e\u63db\u7a4d\u5206\u3092\u884c\u3046. \u7a4d\u5206\u7bc4\u56f2\u306f, <br>$$<br>\\begin{array}{c|ccc}<br>x &amp; \\sqrt{3} &amp; \\rightarrow &amp; \\sqrt{6} \\\\<br>\\hline<br>\\theta &amp; \\frac{\\pi}{6} &amp; \\rightarrow &amp; \\frac{\\pi}{4} \\\\<br>\\end{array}<br>$$\u3067\u3042\u308a, <br>$$<br>dx=2\\sqrt{3}\\cos{\\theta}d\\theta<br>$$\u3068\u306a\u308b\u304b\u3089, <br>$$<br>\\begin{align}<br>\\int_\\sqrt{3}^\\sqrt{6}{\\sqrt{12-x^2}}\\,dx&amp;=\\int_{\\frac{\\pi}{6}}^{\\frac{\\pi}{4}}{\\sqrt{12-\\left(2\\sqrt{3}\\sin{\\theta}\\right)^2}}\\cdot 2\\sqrt{3}\\cos{\\theta}\\,d\\theta\\\\[1.5ex]<br>&amp;=12\\int_{\\frac{\\pi}{6}}^{\\frac{\\pi}{4}}\\sqrt{1-\\sin^2{\\theta}}\\cdot\\cos{\\theta}\\,d\\theta\\\\[1.5ex]<br>&amp;=12\\int_{\\frac{\\pi}{6}}^{\\frac{\\pi}{4}}\\cos^2{\\theta}\\,d\\theta\\,\\,(\\,\\because \u7a4d\u5206\u533a\u9593\u3067\\cos{\\theta}>0\u3088\u308a)\\\\[1.5ex]<br>&amp;=12\\int_{\\frac{\\pi}{6}}^{\\frac{\\pi}{4}}\\frac{1+\\cos{2\\theta}}{2}\\,d\\theta\\\\[1.5ex]<br>&amp;=6\\left[\\theta+\\frac{1}{2}\\sin{2\\theta}\\right]_{\\frac{\\pi}{6}}^{\\frac{\\pi}{4}}\\\\[1.5ex]<br>&amp;=6\\left(\\frac{\\pi}{4}+\\frac{1}{2}-\\frac{\\pi}{6}-\\frac{\\sqrt{3}}{4}\\right)\\\\[1.5ex]<br>&amp;=\\frac{\\pi}{2}+3-\\frac{3\\sqrt{3}}{2}<br>\\end{align}<br>$$\u3068\u8a08\u7b97\u3067\u304d\u308b.<br><br>3\u3064\u76ee\u306e\u7a4d\u5206\u306f, <br>$$<br>\\int_\\sqrt{3}^\\sqrt{6}{x}\\,dx=\\left[\\frac{x^2}{2}\\right]_\\sqrt{3}^\\sqrt{6}=\\frac{3}{2}<br>$$\u3068\u306a\u308b. <br><br>\u3088\u3063\u3066, <br>$$<br>\\begin{align}<br>S&amp;=\\left(\\sqrt{3}-\\frac{4}{3}\\right)+\\left(\\frac{\\pi}{2}+3-\\frac{3\\sqrt{3}}{2}\\right)-\\left(\\frac{3}{2}\\right)\\\\[1.5ex]<br>&amp;=\\frac{\\pi}{2}-\\frac{\\sqrt{3}}{2}+\\frac{1}{6}<br>\\end{align}<br>$$\u3068\u306a\u308b.<\/p>\n\n\n\n<p>\u3084\u306f\u308a, \u4f55\u3082\u8003\u3048\u305a\u30b4\u30ea\u30b4\u30ea\u306b\u7a4d\u5206\u8a08\u7b97\u3067\u6c42\u307e\u308b\u7406\u7cfb\u306e\u89e3\u6cd5\u306e\u65b9\u304c\u697d\u3067\u3059\u306d.<\/p>\n\n\n\n<p>youtube\u3067\u3082\u89e3\u8aac\u3057\u3066\u3044\u307e\u3059.<\/p>\n\n\n\n<iframe width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/pTLJvMYhHK8?si=yzL_fpH29MBI3c4O\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n\n\n\n\n","protected":false},"excerpt":{"rendered":"<p>\u4eca\u56de\u306f\u3053\u3061\u3089\u306e\u554f\u984c\u3092\u89e3\u3044\u3066\u3044\u304d\u307e\u3059. \u4ee5\u4e0b\u306e\u554f\u3044\u306b\u7b54\u3048\u3088.(1) \\(x&gt;1\\), \\(y&gt;1\\)\u306e\u3068\u304d, $$\\log_x{y}+\\log_y{x}\\geq 2$$\u3092\u793a\u305b.(2) \u4ee5\u4e0b\u306e\u9023\u7acb\u4e0d\u7b49\u5f0f\u304c\u8868\u3059\u9818\u57df [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1539,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"swell_btn_cv_data":"","_themeisle_gutenberg_block_has_review":false,"footnotes":""},"categories":[6],"tags":[],"class_list":["post-1466","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tokimakuru"],"_links":{"self":[{"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/posts\/1466","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/math-friend.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1466"}],"version-history":[{"count":91,"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/posts\/1466\/revisions"}],"predecessor-version":[{"id":2221,"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/posts\/1466\/revisions\/2221"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/math-friend.com\/index.php?rest_route=\/wp\/v2\/media\/1539"}],"wp:attachment":[{"href":"https:\/\/math-friend.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1466"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/math-friend.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1466"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/math-friend.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1466"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}