Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
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{"common":{"save":0,"post_id":"6185","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"5398","mon_id":"1158767","chapter_id":"1158801","post_id":"6185","question":"<p>Hàm s\u1ed1 <span class=\"math-tex\">$y = -x^2+2(m-1)x-1$<\/span> ngh\u1ecbch bi\u1ebfn trên <span class=\"math-tex\">$(2;+\\infty)$<\/span> khi giá tr\u1ecb <span class=\"math-tex\">$m$<\/span> th\u1ecfa mãn:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$m \\ge 0$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$m > 0$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$m \\le 3$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$0< m\\le3$<\/span>"],"correct":"3","level":"3","hint":"","answer":"<p>\u0110\u1ed3 th\u1ecb c\u1ee7a hàm s\u1ed1 có tr\u1ee5c \u0111\u1ed1i x\u1ee9ng là \u0111\u01b0\u1eddng th\u1eb3ng <span class=\"math-tex\">$x = m-1$<\/span> . \u0110\u1ed3 th\u1ecb c\u1ee7a hàm s\u1ed1 \u0111ã cho có h\u1ec7 s\u1ed1 <span class=\"math-tex\">$a = -1 < 0$<\/span> nên s\u1ebd \u0111\u1ed3ng bi\u1ebfn trên kho\u1ea3ng <span class=\"math-tex\">$(-\\infty;m-1)$<\/span> và ngh\u1ecbch bi\u1ebfn trên kho\u1ea3ng <span class=\"math-tex\">$(m-1;+\\infty)$<\/span> . <\/p><p>\u0110\u1ec3 hàm s\u1ed1 ngh\u1ecbch bi\u1ebfn trên kho\u1ea3ng <span class=\"math-tex\">$(2;+\\infty)$<\/span> thì <\/p><p><span class=\"math-tex\">$(2;+\\infty) \\subset (m-1;+\\infty)$<\/span> ⇔ <span class=\"math-tex\">$m-1 \\le 2$<\/span> ⇔ <span class=\"math-tex\">$m \\le 3$<\/span> .<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>C.<\/strong> <span class=\"math-tex\">$m \\le 3$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2022-09-04 05:15:56","option_type":"math","len":0},{"id":"5403","mon_id":"1158767","chapter_id":"1158801","post_id":"6185","question":"<p>Giá tr\u1ecb nào c\u1ee7a <span class=\"math-tex\">$m$<\/span> thì \u0111\u1ed3 th\u1ecb c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$y = x^2-3x+2m$<\/span> c\u1eaft tr\u1ee5c hoành t\u1ea1i hai \u0111i\u1ec3m phân bi\u1ec7t?<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$m<-\\dfrac{9}{8}$<\/span>","<strong>B. <\/strong><span class=\"math-tex\">$m>-\\dfrac{9}{8}$<\/span>","<strong>C. <\/strong><span class=\"math-tex\">$m>\\dfrac{9}{8}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$m<\\dfrac{9}{8}$<\/span>"],"correct":"4","level":"3","hint":"","answer":"<p>Ph\u01b0\u01a1ng trình hoành \u0111\u1ed9 giao \u0111i\u1ec3m c\u1ee7a \u0111\u1ed3 th\u1ecb hàm s\u1ed1 và tr\u1ee5c hoành là<\/p><p><span class=\"math-tex\">$x^2-3x+2m=0$<\/span> (1)<\/p><p>\u0110\u1ec3 \u0111\u1ed3 th\u1ecb c\u1eaft tr\u1ee5c hoành t\u1ea1i hai \u0111i\u1ec3m phân bi\u1ec7t thì ph\u01b0\u01a1ng trình (1) có hai nghi\u1ec7m phân bi\u1ec7t<\/p><p>⇔ <span class=\"math-tex\">$\\Delta > 0$<\/span> ⇔ <span class=\"math-tex\">$(-3)^2 - 4 . 1 . 2m > 0$<\/span> ⇔ <span class=\"math-tex\">$9 - 8m > 0$<\/span> ⇔ <span class=\"math-tex\">$m < \\dfrac{9}{8}$<\/span> .<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>D.<\/strong> <span class=\"math-tex\">$m<\\dfrac{9}{8}$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2022-09-04 05:52:49","option_type":"math","len":0},{"id":"5404","mon_id":"1158767","chapter_id":"1158801","post_id":"6185","question":"<p>Giá tr\u1ecb nào c\u1ee7a <span class=\"math-tex\">$m $<\/span> thì \u0111\u1ed3 th\u1ecb c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$y = x^2+x-5m$<\/span> <strong>không c\u1eaft<\/strong> tr\u1ee5c hoành?<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$m<-\\dfrac{1}{20}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$m>-\\dfrac{1}{20}$<\/span>","<strong>C. <\/strong><span class=\"math-tex\">$m < \\dfrac{1}{20}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$m>\\dfrac{1}{20}$<\/span>"],"correct":"1","level":"3","hint":"","answer":"<p>Ph\u01b0\u01a1ng trình hoành \u0111\u1ed9 giao \u0111i\u1ec3m c\u1ee7a \u0111\u1ed3 th\u1ecb hàm s\u1ed1 và tr\u1ee5c hoành là<\/p><p><span class=\"math-tex\">$x^2+x-5m=0$<\/span> (1)<\/p><p>\u0110\u1ec3 \u0111\u1ed3 th\u1ecb hàm s\u1ed1 không c\u1eaft tr\u1ee5c hoành thì ph\u01b0\u01a1ng trình (1) vô nghi\u1ec7m<\/p><p>⇔ <span class=\"math-tex\">$\\Delta < 0$<\/span> ⇔ <span class=\"math-tex\">$1^2-4.1.(-5m ) < 0$<\/span> ⇔ <span class=\"math-tex\">$1+20m < 0$<\/span> ⇔ <span class=\"math-tex\">$m < -\\dfrac{1}{20}$<\/span> .<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"> <strong>A.<\/strong> <span class=\"math-tex\">$m<-\\dfrac{1}{20}$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2022-09-04 05:59:41","option_type":"math","len":0}]}