{"common":{"save":0,"post_id":"769","level":2,"total":20,"point":5,"point_extra":0},"segment":[{"id":"1061","post_id":"769","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":[[1]],"list":[{"point":5,"ques":" T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 nguy\u00ean x, bi\u1ebft: -20 $\\le$ x < 20 ","select":["A. -20","B. 20 ","C. 0","D. -39"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>B\u01b0\u1edbc 1: T\u00ecm c\u00e1c s\u1ed1 nguy\u00ean x th\u1ecfa m\u00e3n -20 $\\le$ x < 20 <br\/>B\u01b0\u1edbc 2: T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 nguy\u00ean x v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c \u1edf b\u01b0\u1edbc 1<br\/><b>L\u01b0u \u00fd: <\/b> <i>Hai s\u1ed1 nguy\u00ean \u0111\u1ed1i nhau c\u00f3 t\u1ed5ng b\u1eb1ng 0<\/i><\/span> <br\/><br\/><span class='basic_left'> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: -20 $\\le$ x < 20 $\\Rightarrow $ x $ \\in$ {-20; -19; -18; ...; 18; 19}<br\/> T\u1ed5ng c\u1ee7a c\u00e1c s\u1ed1 nguy\u00ean x l\u00e0:<br\/>$\\begin{align*}& (-20) + (-19) + (-18) + ... + 18 + 19\\\\&= (-20) + [(-19) + 19] + [(-18) + 18] + ... + 0 \\\\&= (-20) + 0 + 0 + ... + 0\\\\&= -20 \\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> A. -20<\/span><\/span><\/span> <br\/>","column":2}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:48"},{"id":"1062","post_id":"769","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":[[3]],"list":[{"point":5,"ques":" T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 nguy\u00ean x, bi\u1ebft: -10 $\\le$ x < 11 ","select":["A. -20","B. 20 ","C. 0","D. -39"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>B\u01b0\u1edbc 1: T\u00ecm c\u00e1c s\u1ed1 nguy\u00ean x th\u1ecfa m\u00e3n -10 $\\le$ x < 11 <br\/>B\u01b0\u1edbc 2: T\u00ednh t\u1ed5ng c\u00e1c s\u1ed1 nguy\u00ean x v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c \u1edf b\u01b0\u1edbc 1<br\/><b>L\u01b0u \u00fd: <\/b> <i>Hai s\u1ed1 nguy\u00ean \u0111\u1ed1i nhau c\u00f3 t\u1ed5ng b\u1eb1ng 0<\/i><\/span> <br\/><br\/><span class='basic_left'> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: -10 $\\le$ x < 11 $\\Rightarrow $ x $ \\in$ {-10; -9; -8; ...; 8; 9; 10}<br\/> T\u1ed5ng c\u1ee7a c\u00e1c s\u1ed1 nguy\u00ean x l\u00e0:<br\/>$\\begin{align*}& (-10) + (-9) + (-8) + ... + 8 + 9 + 10\\\\&= [(-10) + 10] + [(-9) + 9] + [(-8) + 8] + ... + 0 \\\\&= 0 + 0 + 0 + ... + 0\\\\&= 0 \\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> C. 0<\/span><\/span><\/span> <br\/>","column":2}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:48"},{"id":"1063","post_id":"769","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":5,"ques":" T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c: <br\/>A = x + 5 + (-x) + (-22)","select":["A = 17","A = -17","A = 27","A = -27"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t giao ho\u00e1n, t\u00ednh ch\u1ea5t k\u1ebft h\u1ee3p c\u1ee7a ph\u00e9p c\u1ed9ng \u0111\u1ec3 <b><i>nh\u00f3m c\u00e1c c\u1eb7p s\u1ed1 l\u00e0 s\u1ed1 \u0111\u1ed1i nhau ho\u1eb7c c\u00f3 t\u1ed5ng b\u1eb1ng s\u1ed1 tr\u00f2n ch\u1ee5c, tr\u00f2n tr\u0103m, tr\u00f2n ngh\u00ecn...<\/i><\/b>\u0111\u1ec3 th\u1ef1c hi\u1ec7n t\u00ednh nhanh.<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>$\\begin{align*}A&= x + 5 + (-x) + (-22)\\\\A&= [ x + (-x)] + [5 + (-22)]\\\\A&= 0 + [-(22 - 5)]\\\\A&= 0 + (-17)\\\\A&= -17\\end{align*}$<br\/>V\u1eady ta ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0: <span class='basic_pink'> A = -17<\/span><\/span> <br\/>","column":2}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:48"}]}