{"common":{"save":0,"post_id":"1402","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"1191","post_id":"1402","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":"<span class='basic_left'> Cho $x-y=1$. Gi\u00e1 tr\u1ecb c\u1ee7a \u0111a th\u1ee9c <br\/> $x^3-x^2y-x^2+xy^2-y^3-y^2+5x-5y-5-2012$ l\u00e0: <\/span>","select":["A. $-2011$","B. $-2012$","C. $-2013$ ","D. $-2014$"],"explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Nh\u00f3m $3$ h\u1ea1ng t\u1eed li\u00ean ti\u1ebfp th\u00e0nh m\u1ed9t nh\u00f3m v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: <br\/> $\\begin{align} & Q={{x}^{3}}-{{x}^{2}}y-{{x}^{2}}+x{{y}^{2}}-{{y}^{3}}-{{y}^{2}}+5x-5y-5-2012 \\\\ & \\,\\,\\,\\,\\,=\\left( {{x}^{3}}-{{x}^{2}}y-{{x}^{2}} \\right)+\\left( x{{y}^{2}}-{{y}^{3}}-{{y}^{2}} \\right)+\\left( 5x-5y-5 \\right)-2012 \\\\ & \\,\\,\\,\\,\\,={{x}^{2}}\\left( x-y-1 \\right)+{{y}^{2}}\\left( x-y-1 \\right)+5\\left( x-y-1 \\right)-2012 \\\\ & \\,\\,\\,\\,\\,={{x}^{2}}\\left( 1-1 \\right)+{{y}^{2}}\\left( 1-1 \\right)+5\\left( 1-1 \\right)-2012 \\\\ & \\,\\,\\,\\,\\,=-2012 \\\\ \\end{align}$ <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span> <\/span>","column":4}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:57"},{"id":"1192","post_id":"1402","mon_id":"0","chapter_id":"0","question":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y \u0110\u00fang hay Sai","options":{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00e2y \u0110\u00fang hay Sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" <span class='basic_left'> Cho c\u00e1c \u0111a th\u1ee9c sau: <br\/> $P=5{{x}^{2}}{{y}^{2}}-xy-2{{y}^{3}}-{{y}^{2}}+5{{x}^{4}} $ <br\/> $Q= -2{{x}^{2}}{{y}^{2}}-5xy+{{y}^{3}}-3{{y}^{2}}+2{{x}^{4}} $ <br\/> $N= -{{x}^{2}}{{y}^{2}}+6xy+{{y}^{3}}+6{{y}^{2}}+7$ <br\/> V\u1edbi m\u1ecdi $x;y$ th\u00ec \u00edt nh\u1ea5t m\u1ed9t trong ba \u0111a th\u1ee9c tr\u00ean c\u00f3 gi\u00e1 tr\u1ecb d\u01b0\u01a1ng. <\/span>","select":["\u0110\u00fang","Sai "],"hint":"So s\u00e1nh t\u1ed5ng $P+Q+N$ v\u1edbi $0$","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>X\u00e9t t\u1ed5ng ba \u0111a th\u1ee9c \u0111\u00e3 cho v\u00e0 so s\u00e1nh t\u1ed5ng \u0111\u00f3 v\u1edbi $0$ <br\/> N\u1ebfu $P+Q+N > 0$ th\u00ec kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0111\u00fang. <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> X\u00e9t t\u1ed5ng ba \u0111a th\u1ee9c \u0111\u00e3 cho: <br\/> $\\begin{aligned} & P+Q+N \\\\ & =\\left( 5{{x}^{2}}{{y}^{2}}-xy-2{{y}^{3}}-{{y}^{2}}+5{{x}^{4}} \\right)+\\left( -2{{x}^{2}}{{y}^{2}}-5xy+{{y}^{3}}-3{{y}^{2}}+2{{x}^{4}} \\right)+\\left( -{{x}^{2}}{{y}^{2}}+6xy+{{y}^{3}}+6{{y}^{2}}+7 \\right) \\\\ & =5{{x}^{2}}{{y}^{2}}-xy-2{{y}^{3}}-{{y}^{2}}+5{{x}^{4}}-2{{x}^{2}}{{y}^{2}}-5xy+{{y}^{3}}-3{{y}^{2}}+2{{x}^{4}}-{{x}^{2}}{{y}^{2}}+6xy+{{y}^{3}}+6{{y}^{2}}+7 \\\\ & =\\left( 5{{x}^{2}}{{y}^{2}}-2{{x}^{2}}{{y}^{2}}-{{x}^{2}}{{y}^{2}} \\right)+\\left( -xy-5xy+6xy \\right)+\\left( -2{{y}^{3}}+{{y}^{3}}+{{y}^{3}} \\right)+\\left( -{{y}^{2}}-3{{y}^{2}}+6{{y}^{2}} \\right)+\\left( 5{{x}^{4}}+2{{x}^{4}} \\right)+7 \\\\ & =2{{x}^{2}}{{y}^{2}}+2{{y}^{2}}+7{{x}^{4}}+7 \\\\ & Do\\,\\,\\left\\{ \\begin{aligned} & 2{{x}^{2}}{{y}^{2}}\\ge 0 \\\\ & 2{{y}^{2}}\\ge 0 \\\\ & 7{{x}^{4}}\\ge 0 \\\\ \\end{aligned} \\right.\\Rightarrow 2{{x}^{2}}{{y}^{2}}+2{{y}^{2}}+7{{x}^{4}}+7>0\\,\\,\\,\\,\\forall x;y \\\\ & \\, \\\\ \\end{aligned}$ <br\/> $\\Rightarrow$ V\u1edbi m\u1ecdi $x;y$ th\u00ec \u00edt nh\u1ea5t m\u1ed9t trong ba \u0111a th\u1ee9c tr\u00ean c\u00f3 gi\u00e1 tr\u1ecb d\u01b0\u01a1ng. <br\/><span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang.<\/span><\/span>","column":2}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:57"},{"id":"1193","post_id":"1402","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":"<span class='basic_left'> Cho hai \u0111a th\u1ee9c sau: <br\/> $P=\\left[ \\dfrac{1}{2}a\\,x-2\\left( a\\,x+3 \\right) \\right]-\\left( a\\,x+1 \\right)$ <br\/> $Q=a\\,x-2-\\left[ 3-\\left( a\\,x-1 \\right) \\right]-4$ <br\/> T\u1ed5ng $P+Q$ l\u00e0: <\/span>","select":["A. $\\dfrac{3}{2}a\\,x+16$","B. $-\\dfrac{3}{2}a\\,x-16$","C. $\\dfrac{1}{2}a\\,x+17$ ","D. $-\\dfrac{1}{2}a\\,x-17$"],"explain":"<span class='basic_left'>Ta c\u00f3: <br\/> $\\begin{align} & P+Q \\\\ & =\\left[ \\dfrac{1}{2}a\\,x-2\\left( a\\,x+3 \\right) \\right]-\\left( a\\,x+1 \\right)+a\\,x-2-\\left[ 3-\\left( a\\,x-1 \\right) \\right]-4 \\\\ & =\\dfrac{1}{2}a\\,x-2a\\,x-6-a\\,x-1+a\\,x-2-3+a\\,x-1-4 \\\\ & =\\left( \\dfrac{1}{2}a\\,x-2a\\,x-a\\,x+a\\,x+a\\,x \\right)+\\left( -6-1-2-3-1-4 \\right) \\\\ & =-\\dfrac{1}{2}a\\,x-17 \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span> <\/span>","column":2}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:57"}]}