{"common":{"save":0,"post_id":"7789","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7358","post_id":"7789","mon_id":"1159278","chapter_id":"1159282","question":"<p>V\u1edbi a, b b\u1ea5t k\u1ef3. Ch\u1ecdn kh\u1eb3ng \u0111\u1ecbnh <strong>sai<\/strong>.<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$a^2+3>-2a$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$4a+4\\le a^2+8$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$a^2+1<-a$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$-ab-b^2\\le a^2$<\/span>"],"correct":"3","level":"3","hint":"","answer":"<p>C&acirc;u sai l&agrave;&nbsp;<span style=\"color:#16a085;\"><strong>C.<\/strong>&nbsp;<span class=\"math-tex\">$a^2+1<-a$<\/span>.<\/span><\/p><p><strong>A.<\/strong>&nbsp;<span class=\"math-tex\">$a^2+3>-2a$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$a^2+2a+3>0$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$(a+1)^2+2>0$<\/span>&nbsp;(\u0111&uacute;ng).<\/p><p><strong>B.<\/strong>&nbsp;<span class=\"math-tex\">$4a+4\\le a^2+8$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$a^2-4a+4\\ge0$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$(a-2)^2\\ge0$<\/span>&nbsp;(\u0111&uacute;ng).<\/p><p><strong>C.<\/strong>&nbsp;<span class=\"math-tex\">$a^2+1<-a$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$a^2+a+1<0$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$\\bigg(a+\\dfrac{1}{2}\\bigg)^2+\\dfrac{3}{4}<0$<\/span>&nbsp;(<span style=\"color:#c0392b;\">sai<\/span>).<\/p><p><strong>D.<\/strong>&nbsp;<span class=\"math-tex\">$-ab-b^2\\le a^2$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$a^2+ab+b^2\\ge0$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$\\bigg(a+\\dfrac{b}{2}\\bigg)^2+\\dfrac{3b^2}{4}\\ge0$<\/span>&nbsp;(\u0111&uacute;ng).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-06 09:25:39","option_type":"math","len":0},{"id":"7360","post_id":"7789","mon_id":"1159278","chapter_id":"1159282","question":"<p>Cho x + y &gt; 1. Ch\u1ecdn kh\u1eb3ng \u0111\u1ecbnh \u0111&uacute;ng.<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$x^2+y^2&gt;\\dfrac{1}{2}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$x^2+y^2&lt;\\dfrac{1}{2}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$x^2+y^2=\\dfrac{1}{2}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$x^2+y^2\\le\\dfrac{1}{2}$<\/span>"],"correct":"1","level":"3","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>A.<\/strong>&nbsp;<span class=\"math-tex\">$x^2+y^2&gt;\\dfrac{1}{2}$<\/span>.<\/span><\/p><p>T\u1eeb x + y &gt; 1, b&igrave;nh ph\u01b0\u01a1ng hai v\u1ebf (hai v\u1ebf \u0111\u1ec1u d\u01b0\u01a1ng) \u0111\u01b0\u1ee3c <span class=\"math-tex\">$(x+y)^2&gt;1$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$x^2+2xy+y^2&gt;1$<\/span>&nbsp;(1).<\/p><p>T\u1eeb <span class=\"math-tex\">$(x-y)^2\\ge0$<\/span>&nbsp;suy ra&nbsp;<span class=\"math-tex\">$x^2-2xy+y^2\\ge0$<\/span>&nbsp;(2).<\/p><p>C\u1ed9ng t\u1eebng v\u1ebf (1) v\u1edbi (2)&nbsp;\u0111\u01b0\u1ee3c <span class=\"math-tex\">$2x^2+2y^2&gt;1$<\/span>.<\/p><p>Chia hai v\u1ebf cho&nbsp;2 ta \u0111\u01b0\u1ee3c&nbsp;<span style=\"color:#16a085;\"><span class=\"math-tex\">$x^2+y^2&gt;\\dfrac{1}{2}$<\/span>.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-06 09:32:11","option_type":"math","len":0},{"id":"7361","post_id":"7789","mon_id":"1159278","chapter_id":"1159282","question":"<p>M\u1ed9t tam gi&aacute;c c&oacute; \u0111\u1ed9 d&agrave;i c&aacute;c c\u1ea1nh l&agrave; 3 , <span class=\"math-tex\">$x$<\/span>&nbsp;, 6 ( <span class=\"math-tex\">$x$<\/span>&nbsp;l&agrave; s\u1ed1 nguy&ecirc;n). H\u1ecfi c&oacute; bao nhi&ecirc;u gi&aacute; tr\u1ecb nguy&ecirc;n c\u1ee7a <span class=\"math-tex\">$x$<\/span>&nbsp; \u0111\u1ec3 tam gi&aacute;c \u0111\u01b0\u1ee3c t\u1ea1o th&agrave;nh?<\/p>","options":["<strong>A.<\/strong> 6","<strong>B.<\/strong> 5","<strong>C.<\/strong> 4","<strong>D.<\/strong> 8"],"correct":"2","level":"3","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>B.<\/strong>&nbsp;5<\/span><\/p><p>&Aacute;p d\u1ee5ng b\u1ea5t \u0111\u1eb3ng th\u1ee9c tam gi&aacute;c&nbsp;ta c&oacute;<\/p><p><span class=\"math-tex\">$x$<\/span>&nbsp;&nbsp;+&nbsp;3 &gt; 6&nbsp; &nbsp;=&gt;&nbsp; &nbsp; <span class=\"math-tex\">$x$<\/span>&nbsp; &gt; 3<\/p><p><span class=\"math-tex\">$x$<\/span>&nbsp;&nbsp;+&nbsp;6 &gt; 3&nbsp; &nbsp;=&gt;&nbsp; &nbsp;<span class=\"math-tex\">$x$<\/span>&nbsp; &gt; - 3 (lu&ocirc;n \u0111&uacute;ng v\u1edbi m\u1ecdi&nbsp; <span class=\"math-tex\">$x$<\/span>&nbsp;&nbsp;&gt;3)<\/p><p>3&nbsp; +&nbsp;6 &gt; <span class=\"math-tex\">$x$<\/span>&nbsp;&nbsp; =&gt;&nbsp; &nbsp;<span class=\"math-tex\">$x$<\/span>&nbsp; &lt; 9<\/p><p>M&agrave; x&nbsp;&isin; Z n&ecirc;n x&nbsp;&isin; {4 ; 5 ; 6 ; 7 ; 8}<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-06 09:35:46","option_type":"txt","len":0}]}