{"common":{"save":0,"post_id":"985","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"341","post_id":"985","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["80"],["120"],["192"]]],"list":[{"point":10,"width":80,"type_input":"","ques":" T\u00ecm a, b, c bi\u1ebft: <br\/> $5a - 3b - 3c = -536 $ v\u00e0 $\\dfrac{a}{4} = \\dfrac{b}{6}, \\dfrac{b}{5} = \\dfrac{c}{8} $ <br\/> <br\/> <b> \u0110\u00e1p s\u1ed1:<\/b>$a = $ _input_;$b =$ _input_; $c=$_input_","hint":"Ta n\u1ed1i hai t\u1ec9 l\u1ec7 th\u1ee9c th\u00e0nh m\u1ed9t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau b\u1edfi m\u1eaft x\u00edch l\u00e0 $b$ nh\u01b0 sau: Chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 nh\u1ea5t cho 5 v\u00e0 chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 2 cho $6.$","explain":" Ta n\u1ed1i hai t\u1ec9 l\u1ec7 th\u1ee9c: $\\dfrac{a}{4} = \\dfrac{b}{6}$ v\u00e0 $ \\dfrac{b}{5} = \\dfrac{c}{8} $ th\u00e0nh m\u1ed9t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau b\u1edfi m\u1eaft x\u00edch l\u00e0 $b$ nh\u01b0 sau: <br\/> Chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 nh\u1ea5t cho $5,$ ta \u0111\u01b0\u1ee3c: $\\dfrac{a}{20} = \\dfrac{b}{30}$ <br\/> Chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 2 cho $6,$ ta \u0111\u01b0\u1ee3c: $\\dfrac{b}{30} = \\dfrac{c}{48}$ <br\/> T\u1eeb \u0111\u00f3: $\\dfrac{a}{20} = \\dfrac{b}{30} = \\dfrac{c}{48}$ $\\Rightarrow \\dfrac{5a}{100} = \\dfrac{3b}{90} = \\dfrac{3c}{144}$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $\\dfrac{5a}{100} = \\dfrac{3b}{90} = \\dfrac{3c}{144} = \\dfrac{5a-3b-3c}{100-90-144} = \\dfrac{-536}{-134} = 4 $<br\/> Suy ra: $\\dfrac{a}{20} = 4 \\Rightarrow a = 80 \\\\ \\dfrac{b}{30} = 4 \\Rightarrow b = 120 \\\\ \\dfrac{c}{48} = 4 \\Rightarrow c = 192 $ <br\/> <br\/> <span class='basic_pink'> V\u1eady gi\u00e1 tr\u1ecb c\u1ee7a $a, b, c$ l\u00e0: $\\begin{cases} a = 80 \\\\ b = 120 \\\\ c = 192 \\end{cases}$ <\/span><\/span> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:46"},{"id":"342","post_id":"985","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["63"],["105"],["36"]]],"list":[{"point":10,"width":70,"type_input":"","ques":" <span class='basic_left'> T\u00ecm ba s\u1ed1 nguy\u00ean, bi\u1ebft r\u1eb1ng BCNN c\u1ee7a ch\u00fang b\u1eb1ng $1260.$ T\u1ec9 s\u1ed1 c\u1ee7a s\u1ed1 th\u1ee9 nh\u1ea5t v\u00e0 s\u1ed1 th\u1ee9 hai l\u00e0 $3:5.$ T\u1ec9 s\u1ed1 c\u1ee7a s\u1ed1 th\u1ee9 ba v\u00e0 s\u1ed1 th\u1ee9 nh\u1ea5t l\u00e0 $4:7 $ <\/span> <br\/> <br\/> <u>\u0110\u00e1p s\u1ed1: <\/u> Ba s\u1ed1 l\u1ea7n l\u01b0\u1ee3t l\u00e0: (_input_;_input_;_input_)","hint":" \u0110\u1eb7t \u1ea9n r\u1ed3i \u0111\u01b0a v\u1ec1 c\u00e1c t\u1ec9 l\u1ec7 th\u1ee9c v\u00e0 l\u00e0m xu\u1ea5t hi\u1ec7n d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau","explain":" G\u1ecdi ba s\u1ed1 l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$. Theo gi\u1ea3 thi\u1ebft, ta c\u00f3: <br\/> $\\dfrac{x}{y} = \\dfrac{3}{5}; \\dfrac{z}{x} = \\dfrac{4}{7} \\Rightarrow \\dfrac{x}{3} = \\dfrac{y}{5}; \\dfrac{z}{4} = \\dfrac{x}{7}$ <br\/> Ta c\u00f3:$\\dfrac{x}{3} = \\dfrac{y}{5} \\Rightarrow \\dfrac{x}{21} = \\dfrac{y}{35} \\\\ \\dfrac{z}{4} = \\dfrac{x}{7} \\Rightarrow \\dfrac{z}{12} = \\dfrac{x}{21} \\\\ \\Rightarrow \\dfrac{x}{21} = \\dfrac{y}{35} = \\dfrac{z}{12} $ <br\/> \u0110\u1eb7t: $ \\dfrac{x}{21} = \\dfrac{y}{35} = \\dfrac{z}{12} = k \\Rightarrow \\begin{cases} x = 21k \\\\ y = 35k \\\\ z = 12k \\end{cases}$ <br\/> C\u00f3: BCNN $ (x; y; z) = (21k; 35k; 12k) = (21; 35; 12)k = 420k$ <br\/> Suy ra: $420k = 1260 \\Rightarrow k = 3$ <br\/> <br\/> <span class='basic_pink'> V\u1eady gi\u00e1 tr\u1ecb c\u1ee7a x, y, z l\u00e0 : $ \\begin{cases} x = 21.3 = 63 \\\\ y = 35.3 = 105 \\\\ z = 12.3 = 36 \\end{cases}$ <\/span><\/span>"}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:46"},{"id":"343","post_id":"985","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p s\u1ed1 \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-84"],["63"],["54"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" T\u00ecm $x, y, z$ bi\u1ebft: <br\/> $-3x = 4y; 6y = 7z $ v\u00e0 $x - 2y + 3z = -48$ <br\/> <br\/> <b> \u0110\u00e1p s\u1ed1:<\/b>$x = $ _input_;$y =$ _input_; $z=$_input_","hint":"","explain":" T\u1eeb $ -3x = 4y; 6y = 7z \\Rightarrow \\dfrac{x}{4} = \\dfrac{y}{-3}; \\dfrac{y}{7} = \\dfrac{z}{6}$ <br\/> Ta n\u1ed1i hai t\u1ec9 l\u1ec7 th\u1ee9c: $\\dfrac{x}{4} = \\dfrac{y}{-3}$ v\u00e0 $ \\dfrac{y}{7} = \\dfrac{z}{6} $ th\u00e0nh m\u1ed9t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau b\u1edfi m\u1eaft x\u00edch l\u00e0 $y$ nh\u01b0 sau: <br\/> Chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 nh\u1ea5t cho $-7,$ ta \u0111\u01b0\u1ee3c: $\\dfrac{x}{-28} = \\dfrac{y}{21}$ <br\/> Chia hai v\u1ebf c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c th\u1ee9 2 cho $3,$ ta \u0111\u01b0\u1ee3c: $ \\dfrac{y}{21} = \\dfrac{z}{18}$ <br\/> T\u1eeb \u0111\u00f3: $\\dfrac{x}{-28} = \\dfrac{y}{21} = \\dfrac{z}{18}$ $\\Rightarrow \\dfrac{x}{-28} = \\dfrac{2y}{42} = \\dfrac{3z}{54}$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $\\dfrac{x}{-28} = \\dfrac{2y}{42} = \\dfrac{3z}{54} = \\dfrac{x-2y+3z}{-28-42+54} = \\dfrac{-48}{-16} = 3 $<br\/> Suy ra: $\\dfrac{x}{-28} = 3 \\Rightarrow x = -84 \\\\ \\dfrac{y}{21} = 3 \\Rightarrow y = 63 \\\\ \\dfrac{z}{18} = 3 \\Rightarrow z = 54 $ <br\/> <br\/> <span class='basic_pink'> V\u1eady gi\u00e1 tr\u1ecb c\u1ee7a $x, y, z$ l\u00e0: $\\begin{cases} x = -84 \\\\ y = 63 \\\\ z = 54 \\end{cases}$ <\/span><\/span> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:46"}]}