{"common":{"save":0,"post_id":"6615","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6526","post_id":"6615","mon_id":"1158921","chapter_id":"1158930","question":"<p>R&uacute;t g\u1ecdn ph&acirc;n th\u1ee9c&nbsp;&nbsp;<span class=\"math-tex\">$\\dfrac{x^2-xy+3x-3y}{x^2-y^2}$<\/span>&nbsp;.<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\dfrac{x-3}{x+y}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\dfrac{x-3}{x-y}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$\\dfrac{x+3}{x+y}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\dfrac{x+3}{x-y}$<\/span>"],"correct":"3","level":"3","hint":"","answer":"<p><span class=\"math-tex\">$\\dfrac{x^2-xy+3x-3y}{x^2-y^2}$<\/span>&nbsp;<\/p><p>=&nbsp;<span class=\"math-tex\">$\\dfrac{(x^2-xy)+(3x-3y)}{(x-y)(x+y)}$<\/span><\/p><p>=&nbsp;<span class=\"math-tex\">$\\dfrac{x(x-y)+3(x-y)}{(x-y)(x+y)}$<\/span><\/p><p>=&nbsp;<span class=\"math-tex\">$\\dfrac{(x-y)(x+3)}{(x-y)(x+y)}$<\/span><\/p><p>=&nbsp;<span class=\"math-tex\">$\\dfrac{x+3}{x+y}$<\/span><\/p><p>\u0110&aacute;p &aacute;n \u0111&uacute;ng l&agrave;&nbsp; &nbsp;<span style=\"color:#16a085;\"><strong>C.<\/strong>&nbsp;<span class=\"math-tex\">$\\dfrac{x+3}{x+y}$<\/span>&nbsp;.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-27 01:16:15","option_type":"math","len":0},{"id":"6528","post_id":"6615","mon_id":"1158921","chapter_id":"1158930","question":"<p>\u0110\u1ec3 lo\u1ea1i b\u1ecf x (t&iacute;nh theo %) ch\u1ea5t g&acirc;y &ocirc; nhi\u1ec5m t\u1eeb kh&iacute; th\u1ea3i c\u1ea7n chi ph&iacute; l&agrave; <span class=\"math-tex\">$\\dfrac{1,8x}{100-x}$<\/span>&nbsp; (t\u1ec9 \u0111\u1ed3ng).<\/p><p>N\u1ebfu mu\u1ed1n lo\u1ea1i b\u1ecf 80% ch\u1ea5t g&acirc;y &ocirc; nhi\u1ec5m t\u1eeb kh&iacute; th\u1ea3i c\u1ea7n chi ph&iacute; l&agrave;&nbsp;<\/p>","options":["<strong>A.<\/strong> 7,5 t\u1ec9 \u0111\u1ed3ng","<strong>B.<\/strong> 7,0 t\u1ec9 \u0111\u1ed3ng","<strong>C.<\/strong> 7,8 t\u1ec9 \u0111\u1ed3ng","<strong>D.<\/strong> 7,2 t\u1ec9 \u0111\u1ed3ng"],"correct":"4","level":"3","hint":"","answer":"<p>N\u1ebfu mu\u1ed1n lo\u1ea1i b\u1ecf 80% ch\u1ea5t g&acirc;y &ocirc; nhi\u1ec5m t\u1eeb kh&iacute; th\u1ea3i c\u1ea7n chi ph&iacute; l&agrave;<\/p><p><span class=\"math-tex\">$\\dfrac{1,8.80}{100-80}$<\/span>&nbsp;= 7,2 t\u1ec9 \u0111\u1ed3ng&nbsp; &nbsp; &nbsp;(thay x = 80 v&agrave;o&nbsp;&nbsp;<span class=\"math-tex\">$\\dfrac{1,8x}{100-x}$<\/span>&nbsp;).<\/p><p>\u0110&aacute;p &aacute;n \u0111&uacute;ng l&agrave;&nbsp; <span style=\"color:#16a085;\">&nbsp;<strong>D.<\/strong> 7,2 t\u1ec9 \u0111\u1ed3ng.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-27 01:20:26","option_type":"txt","len":1},{"id":"6530","post_id":"6615","mon_id":"1158921","chapter_id":"1158930","question":"<p>Ch&uacute; An l&aacute;i xe &ocirc; t&ocirc; t\u1eeb H&agrave; N\u1ed9i v\u1ec1 qu&ecirc;. T\u1eeb nh&agrave; ch&uacute; \u0111\u1ebfn \u0111\u01b0\u1eddng cao t\u1ed1c d&agrave;i 20 km v&agrave; ch&uacute; ch\u1ea1y v\u1edbi v\u1eadn t\u1ed1c x km\/h. Tr&ecirc;n 50 km \u0111\u01b0\u1eddng cao t\u1ed1c, xe t\u0103ng v\u1eadn t\u1ed1c th&ecirc;m 50 km\/h n\u1eefa. Ra kh\u1ecfi cao t\u1ed1c, xe ph\u1ea3i ch\u1ea1y th&ecirc;m 30 ph&uacute;t n\u1eefa th&igrave; v\u1ec1 \u0111\u1ebfn qu&ecirc;.<\/p><p>Ph&acirc;n th\u1ee9c bi\u1ec3u th\u1ecb t\u1ed5ng th\u1eddi gian ch&uacute; An \u0111i t\u1eeb H&agrave; N\u1ed9i v\u1ec1 \u0111\u1ebfn qu&ecirc; l&agrave;<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\dfrac{x^2-190x+2000}{2x(x+50)}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\dfrac{x^2+190x+2000}{2x(x+50)}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$\\dfrac{x^2-190x+2000}{2x(x-50)}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\dfrac{x^2-190x-2000}{2x(x-50)}$<\/span>"],"correct":"2","level":"3","hint":"","answer":"<p>Th\u1eddi gian ch&uacute; An \u0111i t\u1eeb nh&agrave; \u0111\u1ebfn cao t\u1ed1c l&agrave;&nbsp;&nbsp;<span class=\"math-tex\">$\\dfrac{20}{x}$<\/span>&nbsp;gi\u1edd.<\/p><p>V&igrave; tr&ecirc;n 50 km \u0111\u01b0\u1eddng cao t\u1ed1c, xe t\u0103ng v\u1eadn t\u1ed1c th&ecirc;m 50 km\/h n\u1eefa n&ecirc;n th\u1eddi gian ch&uacute; An \u0111i tr&ecirc;n cao t\u1ed1c l&agrave;&nbsp;&nbsp;<span class=\"math-tex\">$\\dfrac{50}{x+50}$<\/span>&nbsp; gi\u1edd.<\/p><p>V&igrave; ra&nbsp;kh\u1ecfi cao t\u1ed1c, xe ph\u1ea3i ch\u1ea1y th&ecirc;m 30 ph&uacute;t =&nbsp;<span class=\"math-tex\">$\\dfrac{1}{2}$<\/span>&nbsp;gi\u1edd n\u1eefa th&igrave; v\u1ec1 \u0111\u1ebfn qu&ecirc; n&ecirc;n&nbsp;t\u1ed5ng th\u1eddi gian ch&uacute; An \u0111i t\u1eeb H&agrave; N\u1ed9i v\u1ec1 \u0111\u1ebfn qu&ecirc; l&agrave;<\/p><p><span class=\"math-tex\">$\\dfrac{20}{x}+\\dfrac{50}{x+50}+\\dfrac{1}{2}$<\/span>&nbsp;=&nbsp;<span class=\"math-tex\">$\\dfrac{40x+2000+100x+x^2+50x}{2x(x+50)}$<\/span>&nbsp;=&nbsp;<span class=\"math-tex\">$\\dfrac{x^2+190x+2000}{2x(x+50)}$<\/span>&nbsp; gi\u1edd.<\/p><p>\u0110&aacute;p &aacute;n \u0111&uacute;ng l&agrave;&nbsp; &nbsp;<span style=\"color:#16a085;\"><strong>B.<\/strong>&nbsp;<span class=\"math-tex\">$\\dfrac{x^2+190x+2000}{2x(x+50)}$<\/span>&nbsp;.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-27 01:28:24","option_type":"math","len":0}]}