{"common":{"save":0,"post_id":"794","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"1441","post_id":"794","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["-2"],["1"],["-3"],["3"],["-5"]]],"list":[{"point":10,"width":50,"type_input":"","ques":"Cho bi\u1ec3u th\u1ee9c A = $\\dfrac{4}{n + 1}$; $n \\in \\mathbb{Z}$. T\u00ecm t\u1ea5t c\u1ea3 c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a n \u0111\u1ec3 gi\u00e1 tr\u1ecb c\u1ee7a A l\u00e0 m\u1ed9t s\u1ed1 nguy\u00ean. <br\/> \u0110\u00e1p \u00e1n l\u00e0: $n \\in ${_input_; _input_; _input_; _input_; _input_; _input_}","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> \u0110i\u1ec1u ki\u1ec7n \u0111\u1ec3 A l\u00e0 s\u1ed1 nguy\u00ean th\u00ec n + 1 l\u00e0 \u01b0\u1edbc c\u1ee7a 4 <br\/> T\u1eeb \u0111\u00f3 t\u00ecm c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a n th\u1ecfa m\u00e3n <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> \u0110\u1ec3 $A = \\dfrac{4}{n + 1}$ l\u00e0 s\u1ed1 nguy\u00ean th\u00ec 4 $\\vdots$ (n + 1) hay n + 1$\\in$ \u01af(4) <br\/> M\u00e0 4 c\u00f3 c\u00e1c \u01b0\u1edbc l\u00e0: 1; -1; 2; -2; 4; -4 <br\/> $\\Rightarrow$ n + 1 $\\in$ {1; -1; 2; -2; 4; -4} <br\/> Khi n + 1 = 1 $\\Rightarrow$ n = 0 <br\/> Khi n + 1 = -1 $\\Rightarrow$ n = -2 <br\/> Khi n + 1 = 2 $\\Rightarrow$ n = 1 <br\/> Khi n + 1 = -2 $\\Rightarrow$ n = -3 <br\/> Khi n + 1 = 4 $\\Rightarrow$ n = 3 <br\/> Khi n + 1 = -4 $\\Rightarrow$ n = -5 <br\/> V\u1eady v\u1edbi n $\\in$ {0; -2; 1; -3; 3; -5 } th\u00ec A c\u00f3 gi\u00e1 tr\u1ecb l\u00e0 s\u1ed1 nguy\u00ean <br\/> <span class='basic_pink'>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: 0; -2; 1; -3; 3; -5 <\/span> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:51"},{"id":"1442","post_id":"794","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["-2"],["0"],["1"],["3"]]],"list":[{"point":10,"width":50,"type_input":"","ques":"Cho bi\u1ec3u th\u1ee9c B = $\\dfrac{5}{2n - 1}$; $n \\in \\mathbb{Z}$. T\u00ecm t\u1ea5t c\u1ea3 c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a n \u0111\u1ec3 gi\u00e1 tr\u1ecb c\u1ee7a B l\u00e0 m\u1ed9t s\u1ed1 nguy\u00ean . <br\/> \u0110\u00e1p \u00e1n l\u00e0: $n \\in ${_input_; _input_; _input_; _input_} (t\u1eadp h\u1ee3p gi\u00e1 tr\u1ecb c\u1ee7a n \u0111\u01b0\u1ee3c s\u1eafp x\u1ebfp theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n)","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> \u0110i\u1ec1u ki\u1ec7n \u0111\u1ec3 B l\u00e0 s\u1ed1 nguy\u00ean th\u00ec 2n - 1 l\u00e0 \u01b0\u1edbc c\u1ee7a 5 <br\/> T\u1eeb \u0111\u00f3 t\u00ecm c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a n th\u1ecfa m\u00e3n <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> \u0110\u1ec3 $B = \\dfrac{5}{2n - 1}$ l\u00e0 s\u1ed1 nguy\u00ean th\u00ec 5 $\\vdots$ (2n - 1) hay 2n - 1$\\in$ \u01af(5) <br\/>M\u00e0 5 c\u00f3 c\u00e1c \u01b0\u1edbc l\u00e0: 1; -1; 5; -5 <br\/> $\\Rightarrow$ 2n - 1 $\\in$ {1; -1; 5; -5} <br\/> Khi 2n - 1 = 1 $\\Rightarrow$ n = 1 <br\/> Khi 2n - 1 = -1 $\\Rightarrow$ n = 0 <br\/> Khi 2n - 1 = 5 $\\Rightarrow$ n = 3 <br\/> Khi 2n - 1 = -5 $\\Rightarrow$ n = -2 <br\/> V\u1eady v\u1edbi n $\\in$ {0; 1; 3; -2 } th\u00ec B c\u00f3 gi\u00e1 tr\u1ecb l\u00e0 s\u1ed1 nguy\u00ean<br\/>T\u1eadp h\u1ee3p gi\u00e1 tr\u1ecb n th\u1ecfa m\u00e3n \u0111\u1ea7u b\u00e0i \u0111\u01b0\u1ee3c s\u1eafp x\u1ebfp theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n l\u00e0: n $\\in$ {-2; 0; 1; 3}<br\/> <span class='basic_pink'>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0: -2; 0; 1; 3 <\/span> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:51"},{"id":"1443","post_id":"794","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["8"],["42"],["18"]]],"list":[{"point":10,"width":50,"type_input":"","ques":"H\u00e3y \u0111i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng <br\/> $\\dfrac{2}{7}$ = <div class=\"frac123\"><div class=\"ts\">_input_<\/div><div class=\"ms\">28<\/div><\/div> = <div class=\"frac123\"><div class=\"ts\">12<\/div><div class=\"ms\">_input_<\/div><\/div>= <div class=\"frac123\"><div class=\"ts\">_input_<\/div><div class=\"ms\">63<\/div><\/div>","hint":"D\u1ef1a v\u00e0o kh\u00e1i ni\u1ec7m ph\u00e2n s\u1ed1 b\u1eb1ng nhau","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> G\u1ecdi c\u00e1c s\u1ed1 c\u1ea7n t\u00ecm l\u1ea7n l\u01b0\u1ee3t l\u00e0 a, b, c <br\/> $\\dfrac{2}{7} = \\dfrac{a}{28} = \\dfrac{12}{b} = \\dfrac{c}{63}$ <br\/> Cho l\u1ea7n l\u01b0\u1ee3t c\u00e1c ph\u00e2n s\u1ed1 $\\dfrac{a}{28}; \\dfrac{12}{b}; \\dfrac{c}{63}$ b\u1eb1ng ph\u00e2n s\u1ed1 $\\dfrac{2}{7}$ \u0111\u1ec3 t\u00ecm a, b, c <\/span> <br\/><br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> G\u1ecdi c\u00e1c s\u1ed1 c\u1ea7n t\u00ecm l\u1ea7n l\u01b0\u1ee3t l\u00e0 a, b, c <br\/> Khi \u0111\u00f3: $\\dfrac{2}{7} = \\dfrac{a}{28} = \\dfrac{12}{b} = \\dfrac{c}{63}$ <br\/> V\u00ec: $\\dfrac{2}{7} = \\dfrac{a}{28}$ n\u00ean 2 . 28 = 7 . a <br\/> Do \u0111\u00f3: $a = \\dfrac{2 . 28}{7} = 8$ <br\/> V\u00ec $\\dfrac{2}{7} = \\dfrac{12}{b}$ n\u00ean 2 . b = 7 . 12 <br\/> Do \u0111\u00f3: $b = \\dfrac{7 . 12}{2} = 42$ <br\/> V\u00ec: $\\dfrac{2}{7} = \\dfrac{c}{63}$ n\u00ean 2 . 63 = 7 . c <br\/> Do \u0111\u00f3: $c = \\dfrac{2 . 63}{7} = 18$ <br\/> <span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u1ea7n l\u01b0\u1ee3t l\u00e0: 8; 42; 18 <\/span> "}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:14:51"}]}