{"common":{"save":0,"post_id":"945","level":2,"total":20,"point":5,"point_extra":0},"segment":[{"id":"581","post_id":"945","mon_id":"0","chapter_id":"0","question":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. Khi c\u00e1c gi\u00e1 tr\u1ecb $x_{1}, x_{2}$ c\u1ee7a $x$ c\u00f3 t\u1ed5ng b\u1eb1ng $-1$ th\u00ec hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng $y_{1}, y_{2}$ c\u00f3 t\u1ed5ng b\u1eb1ng 4. Bi\u1ec3u th\u1ee9c li\u00ean h\u1ec7 c\u1ee7a $y$ theo $x$ l\u00e0: <\/span>","select":["A. $ y = -x $ ","B. $ y = 3x $ ","C. $ y = 4x $ ","D. $ y = -4x $"],"explain":" V\u00ec $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, n\u00ean: <br\/> $ y = ax$ (a l\u00e0 h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7, a kh\u00e1c 0) <br\/> Khi \u0111\u00f3 : $ \\begin{cases} y_{1} = a .x_{1} \\\\ y_{2} = a.x_{2} \\end{cases} $ <br\/> Suy ra $ y_{1} + y_{2} = a ( x_{1} + x_{2}) \\\\ \\Rightarrow 4 = a.(-1) \\Rightarrow a = -4 $ <br\/> V\u1eady $ y = -4x$ <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:49"},{"id":"582","post_id":"945","mon_id":"0","chapter_id":"0","question":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> Ba \u0111\u01a1n v\u1ecb kinh doanh \u0111\u1ea7u t\u01b0 v\u1ed1n t\u01b0\u01a1ng \u1ee9ng theo t\u1ec9 l\u1ec7 3;5;7. Khi chia l\u00e3i, \u0111\u01a1n v\u1ecb th\u1ee9 ba \u0111\u01b0\u1ee3c h\u01a1n \u0111\u01a1n v\u1ecb th\u1ee9 nh\u1ea5t l\u00e0 200 000 \u0111\u1ed3ng. Bi\u1ebft r\u1eb1ng ti\u1ec1n l\u00e3i \u0111\u01b0\u1ee3c chia theo t\u1ec9 l\u1ec7 ti\u1ec1n v\u1ed1n. H\u1ecfi t\u1ed5ng s\u1ed1 ti\u1ec1n l\u00e3i l\u00e0 bao nhi\u00eau?<\/span>","select":["A. 550 000 \u0111 ","B. 650 000 \u0111 ","C. 750 000 \u0111 ","D. 850 000 \u0111 "],"explain":" <span class='basic_left'> G\u1ecdi s\u1ed1 ti\u1ec1n l\u00e3i c\u1ee7a c\u00e1c \u0111\u01a1n v\u1ecb t\u01b0\u01a1ng \u1ee9ng l\u00e0 $x, y, z$ (\u0111\u1ed3ng). <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $z \u2013 x$ = 200000 v\u00e0 $ \\dfrac{x}{3} = \\dfrac{y}{5} = \\dfrac{z}{7} $ <br\/> Theo t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x}{3} = \\dfrac{y}{5} = \\dfrac{z}{7} = \\dfrac{z-x}{7-3} = \\dfrac{200000}{4} = 50000 \\\\ \\Rightarrow x = 3.50000 = 150000 \\\\ y = 5.50000 = 250000 \\\\ z = 7.50000 = 350000 $ <br\/> T\u1ed5ng s\u1ed1 ti\u1ec1n l\u00e3i l\u00e0: $x + y + z = 150000 + 250000 + 350000 = 750000$(\u0111\u1ed3ng) <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 09:22:49"},{"id":"583","post_id":"945","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":[[["4"],["6"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho bi\u1ebft $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, $x_{1}$ v\u00e0 $x_{2}$ l\u00e0 hai gi\u00e1 tr\u1ecb kh\u00e1c nhau c\u1ee7a $x$, $y_{1}$ v\u00e0 $y_{2}$ l\u00e0 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a $y$. T\u00ednh $x_{2}$, $y_{2}$ bi\u1ebft $x_{2} + y_{2} = 10, x_{1} = 2, y_{1} = 3 $ <br\/> \u0110\u00e1p s\u1ed1: $ x_{2} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}; y_{2} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} $<\/span>","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: L\u1eadp d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau. <br\/> B\u01b0\u1edbc 2: V\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau \u0111\u1ec3 gi\u1ea3i. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> V\u00ec $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn n\u00ean ta c\u00f3: $\\dfrac{y_{1}}{x_{1}} = \\dfrac{y_{2}}{x_{2}} $ <br\/> $ \\Rightarrow \\dfrac{y_{1}}{y_{2}} = \\dfrac{x_{1}}{x_{2}} = \\dfrac{x_{1}+y_{1}}{x_{2}+y_{2}} = \\dfrac{2+3}{10} = \\dfrac{1}{2} $ <br\/> Do \u0111\u00f3: $ x_{2} = x_{1} : \\dfrac{1}{2} = 2 : \\dfrac{1}{2} = 4 \\\\ y_{2} = y_{1} : \\dfrac{1}{2} = 3 : \\dfrac{1}{2} = 6 $ <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 $ x_{2} = 4, y_{2} = 6 $. <\/span><\/span> "}]}]},"correct":"","level":"2","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:49"}]}