{"id":6980,"date":"2021-07-23T23:20:33","date_gmt":"2021-07-23T14:20:33","guid":{"rendered":"https:\/\/sasamath.com\/blog\/?page_id=6980"},"modified":"2021-08-02T02:17:45","modified_gmt":"2021-08-01T17:17:45","slug":"real-numbers","status":"publish","type":"page","link":"https:\/\/sasamath.com\/blog\/invitation-to-calculus\/real-numbers\/","title":{"rendered":"\uc2e4\uc218\uacc4"},"content":{"rendered":"<div class=\"box itc_intro\">\n<p>\uc774 \uae00\uc740 \u300e\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c\u300f 0\uc7a5 4\uc808\uc758 \ub0b4\uc6a9\uc785\ub2c8\ub2e4.&nbsp; <span class=\"itc_viewcontents\">(<a href=\"..\/\">\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c \ucc28\ub840 \ubcf4\uae30<\/a>)<\/span><\/p>\n<\/div>\n<p>\uc2e4\uc218\uacc4\ub97c \uc815\uc758\ud558\ub294 \ubc29\ubc95\uc740 \uc5ec\ub7ec \uac00\uc9c0\uac00 \uc788\ub2e4. \uc5ec\uae30\uc11c\ub294 \uc2e4\uc218\uacc4\uac00 \ub9cc\uc871\uc2dc\ucf1c\uc57c \ud560 \uc131\uc9c8\uc744 \ub098\uc5f4\ud568\uc73c\ub85c\uc368 \uc2e4\uc218\uacc4\ub97c \uc815\uc758\ud558\uae30\ub85c \ud55c\ub2e4.<\/p>\n<p><!-- ##################################################################### --><\/p>\n<h2 class=\"itc_h2\">\uc2e4\uc218\uacc4\uc758 \uacf5\ub9ac<\/h2>\n<p><span class=\"defined\">\uc2e4\uc218\uacc4<\/span>(real number system)\ub780 \uc9d1\ud569 \\(\\mathbb{R}\\)\uc5d0 <span class=\"defined\">\ub367\uc148<\/span>\uc774\ub77c\uace0 \ubd88\ub9ac\ub294 \uc774\ud56d\uc5f0\uc0b0 \u2018\\(+\\)\u2019\uc640 <span class=\"defined\">\uacf1\uc148<\/span>\uc774\ub77c\uace0 \ubd88\ub9ac\ub294 \uc774\ud56d\uc5f0\uc0b0 \u2018\\(\\cdot\\)\u2019 \uadf8\ub9ac\uace0 \uc21c\uc11c\uad00\uacc4 \u2018\\(\\le\\)\u2019\uac00 \uc8fc\uc5b4\uc838 \uc788\ub294 \uac83\uc774\ub2e4. \ub2e8, \uc774 \uc5f0\uc0b0\uacfc \uad00\uacc4\ub294 \ub2e4\uc74c \uc870\uac74\uc744 \ubaa8\ub450 \ub9cc\uc871\uc2dc\ud0a8\ub2e4.<\/p>\n<ul>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b\\)\uc5d0 \ub300\ud558\uc5ec, \\(a+b\\)\uc640 \\(a\\cdot b\\)\uac00 \ubaa8\ub450 \\(\\mathbb{R}\\)\uc5d0 \uc18d\ud55c\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b\\)\uc5d0 \ub300\ud558\uc5ec, \\(a+b = b+a\\)\uc640 \\(a\\cdot b = b\\cdot a\\)\uac00 \uc131\ub9bd\ud55c\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b,\\) \\(c\\)\uc5d0 \ub300\ud558\uc5ec, \\((a+b)+c = a+(b+c)\\)\uc640 \\((a\\cdot b)\\cdot c = a\\cdot (b\\cdot c)\\)\uac00 \uc131\ub9bd\ud55c\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc5d0 \uc6d0\uc18c \\(0\\)\uc774 \uc874\uc7ac\ud558\uc5ec, \uc784\uc758\uc758 \\(a\\in\\mathbb{R}\\)\uc5d0 \ub300\ud558\uc5ec \\(a+0 = a\\) \uadf8\ub9ac\uace0 \\(0+a = a\\)\ub97c \ub9cc\uc871\uc2dc\ud0a8\ub2e4. \uc774\ub7ec\ud55c \uc870\uac74\uc744 \ub9cc\uc871\uc2dc\ud0a4\ub294 \uc6d0\uc18c \\(0\\)\uc740 \uc720\uc77c\ud558\ub2e4. \uc774 \uc6d0\uc18c \\(0\\)\uc744 <span class=\"defined\">\ub367\uc148\uc5d0 \ub300\ud55c \ud56d\ub4f1\uc6d0<\/span>\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a\\)\uc5d0 \ub300\ud558\uc5ec \\(b\\in\\mathbb{R}\\)\uac00 \uc874\uc7ac\ud558\uc5ec \\(a+b =0\\) \uadf8\ub9ac\uace0 \\(b+a=0\\)\uc744 \ub9cc\uc871\uc2dc\ud0a8\ub2e4. \uac01 \\(a\\)\uc5d0 \ub300\ud558\uc5ec \uc774 \uc870\uac74\uc744 \ub9cc\uc871\uc2dc\ud0a4\ub294 \\(b\\)\ub294 \uc720\uc77c\ud558\ub2e4. \uc774 \uc6d0\uc18c \\(b\\)\ub97c \\(a\\)\uc758 <span class=\"defined\">\ub367\uc148\uc5d0 \ub300\ud55c \uc5ed\uc6d0<\/span>\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. \\(a\\)\uc758 \ub367\uc148\uc5d0 \ub300\ud55c \uc5ed\uc6d0\uc744 \\(-a\\)\uc640 \uac19\uc774 \ub098\ud0c0\ub0b8\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc5d0 \\(0\\)\uc774 \uc544\ub2cc \uc6d0\uc18c \\(1\\)\uc774 \uc874\uc7ac\ud558\uc5ec, \uc784\uc758\uc758 \\(a\\in\\mathbb{R}\\)\uc5d0 \ub300\ud558\uc5ec \\(a \\cdot 1 = a\\) \uadf8\ub9ac\uace0 \\(1\\cdot a = a\\)\ub97c \ub9cc\uc871\uc2dc\ud0a8\ub2e4. \uc774\ub7ec\ud55c \uc870\uac74\uc744 \ub9cc\uc871\uc2dc\ud0a4\ub294 \uc6d0\uc18c \\(1\\)\uc740 \uc720\uc77c\ud558\ub2e4. \uc774 \uc6d0\uc18c \\(1\\)\uc744 <span class=\"defined\">\uacf1\uc148\uc5d0 \ub300\ud55c \ud56d\ub4f1\uc6d0<\/span>\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \\(0\\)\uc774 \uc544\ub2cc \uc784\uc758\uc758 \uc6d0\uc18c \\(a\\)\uc5d0 \ub300\ud558\uc5ec \\(b\\in\\mathbb{R}\\)\uac00 \uc874\uc7ac\ud558\uc5ec \\(a\\cdot b =1\\) \uadf8\ub9ac\uace0 \\(b\\cdot a=1\\)\uc744 \ub9cc\uc871\uc2dc\ud0a8\ub2e4. \uac01 \\(a\\)\uc5d0 \ub300\ud558\uc5ec \uc774 \uc870\uac74\uc744 \ub9cc\uc871\uc2dc\ud0a4\ub294 \\(b\\)\ub294 \uc720\uc77c\ud558\ub2e4. \uc774 \uc6d0\uc18c \\(b\\)\ub97c \\(a\\)\uc758 <span class=\"defined\">\uacf1\uc148\uc5d0 \ub300\ud55c \uc5ed\uc6d0<\/span>\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. \\(a\\)\uc758 \uacf1\uc148\uc5d0 \ub300\ud55c \uc5ed\uc6d0\uc744 \\(a^{-1}\\) \ub610\ub294 \\(1\/a\\)\uc640 \uac19\uc774 \ub098\ud0c0\ub0b8\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a\\)\uc5d0 \ub300\ud558\uc5ec, \\(a\\le a\\)\uac00 \uc131\ub9bd\ud55c\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b\\)\uc5d0 \ub300\ud558\uc5ec, [\\(a\\le b\\) \uadf8\ub9ac\uace0 \\(b\\le a\\)]\uc774\uba74 \\(a=b\\)\uc774\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b,\\) \\(c\\)\uc5d0 \ub300\ud558\uc5ec, [\\(a\\le b\\) \uadf8\ub9ac\uace0 \\(b\\le c\\)]\uc774\uba74 \\(a\\le c\\)\uc774\ub2e4.<\/li>\n<li>\\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b\\)\uc5d0 \ub300\ud558\uc5ec, \\(a\\le b\\) \ub610\ub294 \\(b\\le a\\) \uc911 \ud558\ub098 \uc774\uc0c1\uc774 \uc131\ub9bd\ud55c\ub2e4.<\/li>\n<li>\\(E\\)\uac00 \\(\\mathbb{R}\\)\uc758 \ubd80\ubd84\uc9d1\ud569\uc774\uace0 \uacf5\uc9d1\ud569\uc774 \uc544\ub2c8\uba70 \uc704\ub85c \uc720\uacc4\uc774\uba74, \\(E\\)\uc758 \ucd5c\uc18c\uc0c1\uacc4\uac00 \uc874\uc7ac\ud558\uba70 \uadf8 \ucd5c\uc18c\uc0c1\uacc4\ub294 \\(\\mathbb{R}\\)\uc5d0 \uc18d\ud55c\ub2e4.<\/li>\n<\/ul>\n<p><!-- ##################################################################### --><\/p>\n<h2 class=\"itc_h2\">\ucd5c\uc18c\uc0c1\uacc4 \uc131\uc9c8<\/h2>\n<p>\uc2e4\uc218\uacc4\uc758 \uacf5\ub9ac \uc911 \ub9c8\uc9c0\ub9c9 \uc870\uac74\uc744 \uc81c\uc678\ud55c \ub2e4\ub978 \uc870\uac74\ub4e4\uc740 \uc6b0\ub9ac\uac00 \uce5c\uc219\ud558\uac8c \uc0ac\uc6a9\ud558\ub358 \uc2e4\uc218\uc758 \uc131\uc9c8\uc774\ub2e4. \ud558\uc9c0\ub9cc \ub9c8\uc9c0\ub9c9 \uc870\uac74\uc744 \uc628\uc804\ud558\uac8c \uc774\ud574\ud558\ub824\uba74 \u2018\uc720\uacc4\u2019, \u2018\uc0c1\uacc4\u2019 \uac19\uc740 \uba87 \uac00\uc9c0 \uac1c\ub150\uc744 \uc54c\uc544\uc57c \ud55c\ub2e4.<\/p>\n<p>\\(E\\)\uac00 \\(\\mathbb{R}\\)\uc758 \ubd80\ubd84\uc9d1\ud569\uc774\ub77c\uace0 \ud558\uc790. \ub9cc\uc57d [\ubaa8\ub4e0 \\(x\\in E\\)\uc5d0 \ub300\ud558\uc5ec \\(x\\le b\\)]\ub97c \ub9cc\uc871\uc2dc\ud0a4\ub294 \uc2e4\uc218 \\(b\\)\uac00 \uc874\uc7ac\ud55c\ub2e4\uba74 \u201c\\(E\\)\ub294 \\(b\\)\uc5d0 \uc758\ud558\uc5ec <span class=\"defined\">\uc704\ub85c \uc720\uacc4<\/span>(bounded above)\uc774\ub2e4\u201d\ub77c\uace0 \ub9d0\ud558\uace0 \\(b\\)\ub97c \\(E\\)\uc758 <span class=\"defined\">\uc0c1\uacc4<\/span>(upper bound)\ub77c\uace0 \ubd80\ub978\ub2e4. \ub9cc\uc57d \\(E\\)\uac00 \uacf5\uc9d1\ud569\uc774 \uc544\ub2c8\uace0 \uc704\ub85c \uc720\uacc4\uc774\uba74 \\(E\\)\uc758 \uc0c1\uacc4 \uc911 \uac00\uc7a5 \uc791\uc740 \uac12 \\(b\\)\uac00 \uc874\uc7ac\ud55c\ub2e4. \uadf8\ub7ec\ud55c \uc0c1\uacc4 \\(b\\)\ub97c \\(E\\)\uc758 <span class=\"defined\">\ucd5c\uc18c\uc0c1\uacc4<\/span>(least upper bound) \ub610\ub294 <span class=\"defined\">\uc0c1\ud55c<\/span>(supremum)\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.<\/p>\n<p>\uc720\ub9ac\uc218 \uc9d1\ud569 \\(\\mathbb{Q}\\)\ub294 \uadf8\ub7ec\ud55c \uc131\uc9c8\uc744 \uac16\uc9c0 \uc54a\ub294\ub2e4. \uc608\ucee8\ub300 \ub2e4\uc74c\uacfc \uac19\uc740 \uc9d1\ud569 \\(E\\)\ub97c \uc0b4\ud3b4\ubcf4\uc790.<br \/>\n\\[E = \\left\\{ q\\in \\mathbb{Q} \\,\\vert\\, q^2 < 2 \\right\\}.\\]\n\uba85\ubc31\ud788 \\(E\\)\ub294 \\(\\mathbb{Q}\\)\uc758 \ubd80\ubd84\uc9d1\ud569\uc774\uace0 \uacf5\uc9d1\ud569\uc774 \uc544\ub2c8\uba70 \uc704\ub85c \uc720\uacc4\uc774\ub2e4. \ud558\uc9c0\ub9cc \\(E\\)\uc758 \ucd5c\uc18c\uc0c1\uacc4\uac00 \\(\\mathbb{Q}\\)\uc5d0 \uc874\uc7ac\ud558\uc9c0 \uc54a\ub294\ub2e4. \uadf8 \uc774\uc720\ub294 \ub2e4\uc74c\uacfc \uac19\ub2e4. \\(E\\)\uc758 \ucd5c\uc18c\uc0c1\uacc4\uac00 \\(b\\)\uc774\uace0, \\(b\\)\uac00 \uc720\ub9ac\uc218\ub77c\uace0 \uac00\uc815\ud558\uc790. \uadf8\ub7ec\uba74 \\(b\\)\ub294 \\(\\sqrt{2}\\)\uc640 \uc77c\uce58\ud558\uc9c0 \uc54a\uc73c\ubbc0\ub85c \\(\\sqrt{2}\\)\ubcf4\ub2e4 \ud06c\uac70\ub098 \ub610\ub294 \\(\\sqrt{2}\\)\ubcf4\ub2e4 \uc791\ub2e4. \ub9cc\uc57d \\(b > \\sqrt{2}\\)\ub77c\uba74 \\(\\sqrt{2} < r < b\\)\uc778 \uc720\ub9ac\uc218 \\(r\\)\uac00 \uc874\uc7ac\ud55c\ub2e4. \uadf8\ub7ec\uba74 \\(r\\)\ub294 \\(b\\)\ubcf4\ub2e4 \ub354 \uc791\uc740 \uc0c1\uacc4\uac00 \ub418\ubbc0\ub85c, \\(b\\)\uac00 \ucd5c\uc18c\uc0c1\uacc4\ub77c\ub294 \uac00\uc815\uc5d0 \ubaa8\uc21c\uc774\ub2e4. \ub9cc\uc57d \\(b < \\sqrt{2}\\)\ub77c\uba74 \\(b < s < \\sqrt{2}\\)\uc778 \\(s\\in E\\)\uac00 \uc874\uc7ac\ud55c\ub2e4. \uadf8\ub7ec\uba74 \\(b\\)\ub294 \\(E\\)\uc758 \uc0c1\uacc4\uac00 \uc544\ub2cc \uac83\uc774 \ub418\ubbc0\ub85c \ubaa8\uc21c\uc774\ub2e4.<\/p>\n<p>\uc2e4\uc218\uacc4\uc758 \uacf5\ub9ac \uc911 \ub9c8\uc9c0\ub9c9 \uc870\uac74\uc744 <span class=\"defined\">\ucd5c\uc18c\uc0c1\uacc4 \uc131\uc9c8<\/span>\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. (\u2018\uc644\ube44\uc131 \uacf5\ub9ac\u2019, \u2018\uc0c1\ud55c \uacf5\ub9ac\u2019\ub77c\uace0 \ubd80\ub974\uae30\ub3c4 \ud55c\ub2e4.) \uc774 \uc131\uc9c8\uc740 \uc218\uc5f4\uc758 \uadf9\ud55c\uacfc \ud568\uc218\uc758 \uadf9\ud55c\uc758 \uc774\ub860\uc744 \uc804\uac1c\ud560 \ub54c \uc911\uc694\ud55c \uc5ed\ud560\uc744 \ud55c\ub2e4. \uc989 \ucd5c\uc18c\uc0c1\uacc4 \uc131\uc9c8\uc5d0 \uc758\ud558\uc5ec, \uc2e4\uc218\uc5f4\uc774 \uc218\ub834\ud558\uba74 \uadf8 \uadf9\ud55c\uc740 \ubc18\ub4dc\uc2dc \uc2e4\uc218\uc774\ub2e4. \ubc18\uba74 \uc720\ub9ac\uc218\uc5f4\uc740 \uc218\ub834\ud558\ub354\ub77c\ub3c4 \uadf8 \uadf9\ud55c\uc774 \uc720\ub9ac\uc218\uac00 \uc544\ub2d0 \uc218 \uc788\ub2e4. \uc774\uc640 \uac19\uc740 \ub9e5\ub77d\uc5d0\uc11c \u201c\uc2e4\uc218\uacc4\ub294 \uc644\ube44\uc131(completeness property)\uc744 \uac00\uc9c4\ub2e4\u201d\ub77c\uace0 \ub9d0\ud55c\ub2e4.<\/p>\n<p><!-- ##################################################################### --><\/p>\n<h2 class=\"itc_h2\">\uad6c\uac04<\/h2>\n<p><span class=\"defined\">\uad6c\uac04<\/span>\uc774\ub780 \ub450 \uc2e4\uc218 \uc0ac\uc774\uc5d0 \uc788\ub294 \uc218\ub4e4\uc758 \ubaa8\uc784\uc774\ub2e4. \uad6c\uac04\uc740 \ub124 \uac00\uc9c0 \ud615\ud0dc\uac00 \uc788\uc73c\uba70, \uac01\uac01\uc758 \uc815\uc758\ub294 \ub2e4\uc74c\uacfc \uac19\ub2e4.<br \/>\n\\[\\begin{align}<br \/>\n[a,\\,b] &#038;= \\left\\{ x\\in \\mathbb{R} \\,\\vert\\, a \\le x \\le b \\right\\}, \\\\[6pt]<br \/>\n(a,\\,b) &#038;= \\left\\{ x\\in \\mathbb{R} \\,\\vert\\, a < x < b \\right\\}, \\\\[6pt]\n[a,\\,b) &#038;= \\left\\{ x\\in \\mathbb{R} \\,\\vert\\, a \\le x < b \\right\\}, \\\\[6pt]\n(a,\\,b] &#038;= \\left\\{ x\\in \\mathbb{R} \\,\\vert\\, a < x \\le b \\right\\}.\n\\end{align}\\]\n\n\uccab \ubc88\uc9f8 \ud615\ud0dc\uc758 \uad6c\uac04\uc744 <span class=\"defined\">\ub2eb\ud78c\uad6c\uac04<\/span>(closed interval)\uc774\ub77c\uace0 \ubd80\ub974\uba70, \ub450 \ubc88\uc9f8 \ud615\ud0dc\uc758 \uad6c\uac04\uc744 <span class=\"defined\">\uc5f4\ub9b0\uad6c\uac04<\/span>(open interval)\uc774\ub77c\uace0 \ubd80\ub978\ub2e4. \uc138 \ubc88\uc9f8 \ud615\ud0dc\uc640 \ub124 \ubc88\uc9f8 \ud615\ud0dc\uc758 \uad6c\uac04\uc744 <span class=\"defined\">\ubc18\uc5f4\ub9b0\uad6c\uac04<\/span>(half-open interval) \ub610\ub294 <span class=\"defined\">\ubc18\ub2eb\ud78c\uad6c\uac04<\/span>(half-closed interval)\uc774\ub77c\uace0 \ubd80\ub978\ub2e4.<\/p>\n<p>\ub9cc\uc57d \\(a\\ge b\\)\uc774\uba74 \\((a,\\,b),\\) \\([a,\\,b),\\) \\((a,\\,b]\\)\ub294 \ubaa8\ub450 \uacf5\uc9d1\ud569\uc774\ub2e4. \ub9cc\uc57d \\(a=b\\)\uc774\uba74 \\([a,\\,b]\\)\ub294 \uc6d0\uc18c\uac00 \ud558\ub098\uc778 \uc9d1\ud569 \\(\\left\\{a \\right\\}\\)\uc774\ub2e4. \ub9cc\uc57d \\(a > b\\)\uc774\uba74 \\([a,\\,b],\\) \\((a,\\,b),\\) \\([a,\\,b),\\) \\((a,\\,b]\\)\ub294 \ubaa8\ub450 \uacf5\uc9d1\ud569\uc774\ub2e4.<\/p>\n<p>\\(a \\le b\\)\uc77c \ub54c, \uad6c\uac04\uc758 <span class=\"defined\">\uae38\uc774<\/span>\ub97c \\(b-a\\)\ub85c \uc815\uc758\ud55c\ub2e4. \ub9cc\uc57d \\(a > b\\)\uc774\uba74 \uad6c\uac04\uc758 \uae38\uc774\ub97c \\(0\\)\uc73c\ub85c \uc815\uc758\ud55c\ub2e4. \ub9cc\uc57d \\(a < b\\)\uc774\uba74, \uad6c\uac04\uc774 <span class=\"defined\">\uc591\uc218 \uae38\uc774\ub97c \uac00\uc9c4\ub2e4<\/span>(nondegenerate)\ub77c\uace0 \ub9d0\ud55c\ub2e4.<\/p>\n<p><!-- ##################################################################### --><br \/>\n<!--\n\n\n<h2 class=\"itc_h2\">\uc81c\ubaa9<\/h2>\n\n\n--><\/p>\n<p><!--\n\n\n\n<div class=\"theorem margintop2\">\n\n\n<p><span class=\"theorem\">\uc815\ub9ac 1.<\/span>\n\n\n<\/p>\n\n<\/div>\n\n\n\n\n\n<div class=\"proof\">\n\n\n<p class=\"proofname\">\uc99d\uba85.<\/p>\n\n\n\n\n<p>\n\n<span class=\"qed\"><\/span><\/p>\n\n<\/div>\n\n\n\n\n########\n\n\u201c\u201d\n\u2018\u2019\n\n\n\n<div class=\"example\">\n\n\n<p><span class=\"example\">\ubcf4\uae30 1.<\/span>\n\n<\/p>\n\n<\/div>\n\n\n\n\n\n<h2 class=\"itc_h2\"><\/h2>\n\n\n\n--><\/p>\n<p><!--\n\n\n<div style=\"display: none; visibility: hidden;\">\n\\[\n\\newcommand{\\Hom}{{\\operatorname{Hom}}}\n\\newcommand{\\Mat}{{\\operatorname{Mat}}}\n\\newcommand{\\proj}{{\\operatorname{proj}}}\n\\newcommand{\\adj}{{\\operatorname{adj}}}\n\\]\n<\/div>\n\n\n--><\/p>\n<div class=\"box itc_prev_next_box\">\n<ul class=\"itc_ul\">\n<li class=\"itc_li_prev\">\uc55e\uc758 \uae00 : <a href=\"..\/infinite-sets\">\uc720\ud55c\uc9d1\ud569\uacfc \ubb34\ud55c\uc9d1\ud569<\/a><\/li>\n<li class=\"itc_li_next\">\ub2e4\uc74c \uae00 : <a href=\"..\/complex-numbers\">\ud589\ub82c\uacfc \ubcf5\uc18c\uc218<\/a><\/li>\n<\/ul>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\uc774 \uae00\uc740 \u300e\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c\u300f 0\uc7a5 4\uc808\uc758 \ub0b4\uc6a9\uc785\ub2c8\ub2e4.&nbsp; (\ubbf8\uc801\ubd84\ud559 \uccab\uac78\uc74c \ucc28\ub840 \ubcf4\uae30) \uc2e4\uc218\uacc4\ub97c \uc815\uc758\ud558\ub294 \ubc29\ubc95\uc740 \uc5ec\ub7ec \uac00\uc9c0\uac00 \uc788\ub2e4. \uc5ec\uae30\uc11c\ub294 \uc2e4\uc218\uacc4\uac00 \ub9cc\uc871\uc2dc\ucf1c\uc57c \ud560 \uc131\uc9c8\uc744 \ub098\uc5f4\ud568\uc73c\ub85c\uc368 \uc2e4\uc218\uacc4\ub97c \uc815\uc758\ud558\uae30\ub85c \ud55c\ub2e4. \uc2e4\uc218\uacc4\uc758 \uacf5\ub9ac \uc2e4\uc218\uacc4(real number system)\ub780 \uc9d1\ud569 \\(\\mathbb{R}\\)\uc5d0 \ub367\uc148\uc774\ub77c\uace0 \ubd88\ub9ac\ub294 \uc774\ud56d\uc5f0\uc0b0 \u2018\\(+\\)\u2019\uc640 \uacf1\uc148\uc774\ub77c\uace0 \ubd88\ub9ac\ub294 \uc774\ud56d\uc5f0\uc0b0 \u2018\\(\\cdot\\)\u2019 \uadf8\ub9ac\uace0 \uc21c\uc11c\uad00\uacc4 \u2018\\(\\le\\)\u2019\uac00 \uc8fc\uc5b4\uc838 \uc788\ub294 \uac83\uc774\ub2e4. \ub2e8, \uc774 \uc5f0\uc0b0\uacfc \uad00\uacc4\ub294 \ub2e4\uc74c \uc870\uac74\uc744 \ubaa8\ub450 \ub9cc\uc871\uc2dc\ud0a8\ub2e4. \\(\\mathbb{R}\\)\uc758 \uc784\uc758\uc758 \uc6d0\uc18c \\(a,\\) \\(b\\)\uc5d0 \ub300\ud558\uc5ec, \\(a+b\\)\uc640 \\(a\\cdot b\\)\uac00&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":6620,"menu_order":14,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"class_list":["post-6980","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/pages\/6980","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/comments?post=6980"}],"version-history":[{"count":8,"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/pages\/6980\/revisions"}],"predecessor-version":[{"id":7044,"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/pages\/6980\/revisions\/7044"}],"up":[{"embeddable":true,"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/pages\/6620"}],"wp:attachment":[{"href":"https:\/\/sasamath.com\/blog\/wp-json\/wp\/v2\/media?parent=6980"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}