{"common":{"save":0,"post_id":"1025","level":2,"total":20,"point":5,"point_extra":0},"segment":[{"id":"521","post_id":"1025","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["4"]]],"list":[{"width":50,"type_input":"","point":5,"ques":"Cho M = $4 - |5x + 3| $ T\u00ednh gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t c\u1ee7a M <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> max M = _input_","hint":"D\u1ef1a v\u00e0o t\u00ednh ch\u1ea5t $|A| \\geq 0; -|A| \\leq 0 $ ","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> D\u1ef1a v\u00e0o t\u00ednh ch\u1ea5t $|A| \\geq 0; -|A| \\leq 0 $ <br\/> D\u1ea5u ''='' x\u1ea9y ra khi v\u00e0 ch\u1ec9 khi A = 0. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3 $|5x + 3| \\geq 0 $ <br\/> Suy ra $ 4 - |5x + 3| \\leq 4$ <br\/> V\u1eady gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t c\u1ee7a M l\u00e0 4 khi $5x + 3 = 0 \\Leftrightarrow x = \\dfrac{-3}{5} $ <br\/> <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 4 <\/span><\/span>"}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:48"},{"id":"522","post_id":"1025","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":" S\u1ed1 h\u1ecdc sinh 3 l\u1edbp 7A, 7B, 7C c\u1ee7a m\u1ed9t tr\u01b0\u1eddng t\u1ec9 l\u1ec7 v\u1edbi 10; 9; 8. S\u1ed1 h\u1ecdc sinh l\u1edbp 7A nhi\u1ec1u h\u01a1n s\u1ed1 h\u1ecdc sinh l\u1edbp 7C l\u00e0 10 h\u1ecdc sinh. S\u1ed1 h\u1ecdc sinh c\u1ee7a l\u1edbp 7C l\u00e0: ","select":["A. 50 h\u1ecdc sinh","B. 45 h\u1ecdc sinh ","C. 40 h\u1ecdc sinh ","D. 55 h\u1ecdc sinh "],"hint":" \u0110\u1eb7t \u1ea9n r\u1ed3i gi\u1ea3i b\u00e0i to\u00e1n. ","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> T\u00ecm c\u00e1c s\u1ed1 h\u1ea1ng trong m\u1ed9t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau bi\u1ebft t\u1ed5ng, hi\u1ec7u c\u1ee7a c\u00e1c s\u1ed1 h\u1ea1ng \u0111\u00f3<\/b> <br\/> <i><u> Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i <\/i> <\/u> <br\/> N\u1ebfu $\\dfrac{x}{a} = \\dfrac{y}{b} = \\dfrac{z}{c}$ v\u00e0 $x - z = M$ <br\/> th\u00ec $\\dfrac{x}{a} = \\dfrac{y}{b} = \\dfrac{z}{c} = \\dfrac{x-z}{a-c} = \\dfrac{M}{a-c}$ <br\/> T\u1eeb \u0111\u00f3 t\u00ecm \u0111\u01b0\u1ee3c $x, y, z$ <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> G\u1ecdi s\u1ed1 h\u1ecdc sinh c\u1ee7a 3 l\u1edbp 7A, 7B, 7C l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ (h\u1ecdc sinh) ($x, y, z$ nguy\u00ean d\u01b0\u01a1ng) <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $ \\dfrac{x}{10} = \\dfrac{y}{9} = \\dfrac{z}{8}$ v\u00e0 $x - z = 10$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $\\dfrac{x}{10} = \\dfrac{y}{9} = \\dfrac{z}{8} = \\dfrac{x-z}{10-8} = \\dfrac{10}{2} = 5 $ <br\/> Suy ra $ \\dfrac{z}{8} = 5 \\Rightarrow z = 8.5 = 40 $ <br\/> V\u1eady s\u1ed1 h\u1ecdc sinh l\u1edbp 7C l\u00e0 40 (h\u1ecdc sinh) . <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span>","column":2}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:48"},{"id":"523","post_id":"1025","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["40"],["28"],["48"]]],"list":[{"width":50,"type_input":"","point":5,"ques":" <center><img src='img\/2.jpg'\/><\/center> T\u00ecm $x, y, z$ bi\u1ebft: <br\/> $ 42x = 60y = 35z $ v\u00e0 $x - y + z = 60 $ <br\/><br\/>$x = $ _input_;$y =$ _input_; $z=$_input_","hint":" T\u1eeb: $42x = 60y = 35z $ ta chia cho BCNN[42; 60; 35] = 420, ta \u0111\u01b0\u1ee3c: <br\/> $ \\dfrac{x}{10} = \\dfrac{y}{7} = \\dfrac{z}{12} $","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> T\u00ecm c\u00e1c s\u1ed1 h\u1ea1ng trong m\u1ed9t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau bi\u1ebft t\u1ed5ng, hi\u1ec7u c\u1ee7a c\u00e1c s\u1ed1 h\u1ea1ng \u0111\u00f3<\/b> <br\/> <i><u> Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i <\/i> <\/u> <br\/> N\u1ebfu $\\dfrac{x}{a} = \\dfrac{y}{b} = \\dfrac{z}{c}$ v\u00e0 $x - y + z = M$ <br\/> th\u00ec $\\dfrac{x}{a} = \\dfrac{y}{b} = \\dfrac{z}{c} = \\dfrac{x-y+z}{a-b+c} = \\dfrac{M}{a-b+c}$ <br\/> T\u1eeb \u0111\u00f3 t\u00ecm \u0111\u01b0\u1ee3c $x, y, z$ <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> T\u1eeb: $42x = 60y = 35z $ ta chia cho BCNN[42; 60; 35] = 420, ta \u0111\u01b0\u1ee3c: <br\/> $ \\dfrac{42x}{420} = \\dfrac{60y}{420} = \\dfrac{35z}{420} $ hay $ \\dfrac{x}{10} = \\dfrac{y}{7} = \\dfrac{z}{12} $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $\\dfrac{x}{10} = \\dfrac{y}{7} = \\dfrac{z}{12} = \\dfrac{x-y+z}{10-7+12} = \\dfrac{60}{15} = 4 $ <br\/> Suy ra $ \\dfrac{x}{10} = 4 \\Rightarrow x = 10.4 = 40 \\\\ \\dfrac{y}{7} = 4 \\Rightarrow y = 7.4 = 28 \\\\ \\dfrac{z}{12} = 4 \\Rightarrow z = 12.4 = 48 $ <br\/> <br\/> <span class='basic_pink'> V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u1ea7n l\u01b0\u1ee3t l\u00e0 40; 28; 48 <\/span><\/span>"}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:48"}]}