{"common":{"save":0,"post_id":"8069","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8813","post_id":"8069","mon_id":"1159278","chapter_id":"1159330","question":"<p>M\u1ed9t ng\u01b0\u1eddi \u0111i xe máy t\u1eeb A \u0111\u1ebfn B, v\u1edbi v\u1eadn t\u1ed1c 30 km\/h. Lúc v\u1ec1 ng\u01b0\u1eddi \u0111ó \u0111i v\u1edbi v\u1eadn t\u1ed1c 24 km\/h. Do \u0111ó th\u1eddi gian v\u1ec1 lâu h\u01a1n th\u1eddi gian \u0111i là 30 phút. G\u1ecdi th\u1eddi gian lúc \u0111i là x (x > 0) (gi\u1edd) thì ph\u01b0\u01a1ng trình c\u1ee7a bài toán là<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\dfrac{5x}{4}-x=\\dfrac{1}{2}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\dfrac{5x}{4}+x=\\dfrac{1}{2}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$x-\\dfrac{5x}{4}=\\dfrac{1}{2}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\dfrac{5x}{4}-x=-\\dfrac{1}{2}$<\/span>"],"correct":"1","level":"2","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> <span class=\"math-tex\">$\\dfrac{5x}{4}-x=\\dfrac{1}{2}$<\/span>.<\/span><\/p><p>\u0110\u1ed5i 30 phút = <span class=\"math-tex\">$\\dfrac{1}{2}$<\/span> gi\u1edd.<\/p><p>Quãng \u0111\u01b0\u1eddng AB dài là: 30x (km).<\/p><p>Th\u1eddi gian ng\u01b0\u1eddi \u0111ó \u0111i quãng \u0111\u01b0\u1eddng AB lúc v\u1ec1 là: <span class=\"math-tex\">$\\dfrac{30x}{24}=\\dfrac{5x}{4}$<\/span> (gi\u1edd).<\/p><p>Theo \u0111\u1ec1 bài ta có ph\u01b0\u01a1ng trình: <span class=\"math-tex\">$\\dfrac{5x}{4}-x=\\dfrac{1}{2}$<\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-23 09:10:26","option_type":"math","len":0},{"id":"8814","post_id":"8069","mon_id":"1159278","chapter_id":"1159330","question":"<p>Cho hàm s\u1ed1 <span class=\"math-tex\">$y=(2m+1)x^2$<\/span> (m là tham s\u1ed1). Tìm các giá tr\u1ecb c\u1ee7a m \u0111\u1ec3 hàm s\u1ed1 \u0111i qua \u0111i\u1ec3m <span class=\"math-tex\">$A\\bigg(\\dfrac{2}{3};\\dfrac{4}{3}\\bigg)$<\/span>.<\/p>","options":["<strong>A.<\/strong> m = 0","<strong>B.<\/strong> m = –1","<strong>C.<\/strong> m = 2","<strong>D.<\/strong> m = 1"],"correct":"4","level":"2","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D.<\/strong> m = 1.<\/span><\/p><p>Thay <span class=\"math-tex\">$x=\\dfrac{2}{3};y=\\dfrac{4}{3}$<\/span> ta \u0111\u01b0\u1ee3c <span class=\"math-tex\">$(2m+1).\\dfrac{4}{9}=\\dfrac{4}{3}$<\/span> suy ra m = 1.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-23 09:13:48","option_type":"txt","len":1},{"id":"8836","post_id":"8069","mon_id":"1159278","chapter_id":"1159330","question":"<p>Ph\u01b0\u01a1ng trình <span class=\"math-tex\">$-5x^2-4x+1=0$<\/span> có bao nhiêu nghi\u1ec7m là s\u1ed1 t\u1ef1 nhiên?<\/p>","options":["<strong>A.<\/strong> 0","<strong>B.<\/strong> 1","<strong>C.<\/strong> 2","<strong>D.<\/strong> 3"],"correct":"1","level":"2","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> 0.<\/span><\/p><p><span class=\"math-tex\">$\\Delta=16+4.5.1=36$<\/span> > 0 nên ph\u01b0\u01a1ng trình có hai nghi\u1ec7m phân bi\u1ec7t<\/p><p><span class=\"math-tex\">$x=\\dfrac{4+\\sqrt{36}}{-10}=-1$<\/span> ho\u1eb7c <span class=\"math-tex\">$x=\\dfrac{4-\\sqrt{36}}{-10}=\\dfrac{1}{5}$<\/span><\/p><p>V\u1eady ph\u01b0\u01a1ng trình không có nghi\u1ec7m nào là s\u1ed1 t\u1ef1 nhiên.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-26 08:06:25","option_type":"txt","len":0}]}
