Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
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{"common":{"save":0,"post_id":"7947","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8645","post_id":"7947","mon_id":"1159278","chapter_id":"1159330","question":"<p>Ph\u01b0\u01a1ng trình <span class=\"math-tex\">$(m^2+2)x^2-5=0$<\/span> v\u1edbi <span class=\"math-tex\">$m\\in \\mathbb R$<\/span> có nghi\u1ec7m:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$x = \\sqrt{\\dfrac{-5}{m^2+2}}$<\/span>; <span class=\"math-tex\">$x =-\\sqrt{\\dfrac{-5}{m^2+2}}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$x = \\sqrt{\\dfrac{5}{m^2+2}}$<\/span>; <span class=\"math-tex\">$x =\\sqrt{\\dfrac{-5}{m^2+2}}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$x = \\sqrt{\\dfrac{5}{m^2+2}}$<\/span>; <span class=\"math-tex\">$x =-\\sqrt{\\dfrac{5}{m^2+2}}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$x = \\sqrt{\\dfrac{m^2+2}{5}}$<\/span>; <span class=\"math-tex\">$x = -\\sqrt{\\dfrac{m^2+2}{5}}$<\/span>"],"correct":"3","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> <span class=\"math-tex\">$x = \\sqrt{\\dfrac{5}{m^2+2}}$<\/span>; <span class=\"math-tex\">$x =-\\sqrt{\\dfrac{5}{m^2+2}}$<\/span><\/span><\/p><p><span class=\"math-tex\">$(m^2+2)x^2-5=0$<\/span><\/p><p>suy ra <span class=\"math-tex\">$x^2=\\dfrac{5}{m^2+2}$<\/span><\/p><p>suy ra <span class=\"math-tex\">$x = \\sqrt{\\dfrac{5}{m^2+2}}$<\/span> ho\u1eb7c <span class=\"math-tex\">$x =-\\sqrt{\\dfrac{5}{m^2+2}}$<\/span><\/p><p>(vì <span class=\"math-tex\">$m^2\\ge 0$<\/span> v\u1edbi m\u1ecdi m nên <span class=\"math-tex\">$m^2+2> 0$<\/span> v\u1edbi m\u1ecdi m).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-17 10:13:49","option_type":"math","len":0},{"id":"8647","post_id":"7947","mon_id":"1159278","chapter_id":"1159330","question":"<p>V\u1edbi giá tr\u1ecb nào c\u1ee7a tham s\u1ed1 m thì ph\u01b0\u01a1ng trình <span class=\"math-tex\">$4x^2+m^2x+4m=0$<\/span> có nghi\u1ec7m x = 1?<\/p>","options":["<strong>A.<\/strong> m = –4","<strong>B.<\/strong> m = 4","<strong>C.<\/strong> m = 2","<strong>D.<\/strong> m = –2"],"correct":"4","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#1abc9c;\"><\/span><span style=\"color:#16a085;\"><strong>D.<\/strong> m = –2<\/span><\/p><p>\u0110\u1ec3 ph\u01b0\u01a1ng trình <span class=\"math-tex\">$4x^2+m^2x+4m=0$<\/span> có nghi\u1ec7m x = 1 thì<\/p><p><span class=\"math-tex\">$4.1^2+m^2.1+4m=0$<\/span> hay <span class=\"math-tex\">$m^2+4m+4=0$<\/span> hay <span class=\"math-tex\">$(m+2)^2=0$<\/span> suy ra m = –2.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-17 10:17:05","option_type":"txt","len":1},{"id":"8650","post_id":"7947","mon_id":"1159278","chapter_id":"1159330","question":"<p>Có bao nhiêu giá tr\u1ecb c\u1ee7a m \u0111\u1ec3 ph\u01b0\u01a1ng trình <span class=\"math-tex\">$x^2-(2m+1)x+m^2-2m+3=0$<\/span> có nghi\u1ec7m <span class=\"math-tex\">$x=2$<\/span>?<\/p>","options":["<strong>A.<\/strong> 0","<strong>B.<\/strong> 1","<strong>C.<\/strong> 2","<strong>D.<\/strong> 3"],"correct":"3","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> 2<\/span><\/p><p>\u0110\u1ec3 ph\u01b0\u01a1ng trình <span class=\"math-tex\">$x^2-(2m+1)x+m^2-2m+3=0$<\/span> có nghi\u1ec7m <span class=\"math-tex\">$x=2$<\/span> thì<\/p><p><span class=\"math-tex\">$2^2-(2m+1).2+m^2-2m+3=0$<\/span> hay <span class=\"math-tex\">$m^2-6m+5=0$<\/span><\/p><p>suy ra <span class=\"math-tex\">$(m-1)(m-5)=0$<\/span> suy ra m = 1 ho\u1eb7c m = 5.<\/p><p>V\u1eady có 2 giá tr\u1ecb c\u1ee7a m \u0111\u1ec3 ph\u01b0\u01a1ng trình có nghi\u1ec7m x = 2.<\/p>","type":"choose","extra_type":"star","time":"0","user_id":"127","test":"0","date":"2024-11-17 10:26:36","option_type":"txt","len":0}]}