Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
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{"common":{"save":0,"post_id":"6495","level":1,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6907","mon_id":"1158767","chapter_id":"1158892","post_id":"6495","question":"<p>C\u1eb7p \u0111i\u1ec3m nào là các tiêu \u0111i\u1ec3m c\u1ee7a elip (E): <span class=\"math-tex\">$\\dfrac{x^2}{25}+\\dfrac{y^2}{16}=1$<\/span> ?<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$F_{1,2} = (0; \\pm1)$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$F_{1,2} = (\\pm1;0)$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$F_{1,2} = (\\pm3;0)$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$F_{1,2} = (1; \\pm2)$<\/span>"],"correct":"3","level":"1","hint":"","answer":"<p>Ta có a² = 25 ; b² = 16 ⇒ c² = a² – b² = 9 ⇒ c = 3 ⇒ <span class=\"math-tex\">$F_{1,2} = (\\pm3;0)$<\/span>.<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>C.<\/strong> <span class=\"math-tex\">$F_{1,2} = (\\pm3;0)$<\/span><\/span> .<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-05-30 06:42:18","option_type":"math","len":0},{"id":"6908","mon_id":"1158767","chapter_id":"1158892","post_id":"6495","question":"<p>Cho Elip (E): <span class=\"math-tex\">$\\dfrac{x^2}{9}+\\dfrac{y^2}{4}=1$<\/span> . M\u1ec7nh \u0111\u1ec1 nào \u0111úng trong các m\u1ec7nh \u0111\u1ec1 sau?<\/p>","options":["<strong>A. <\/strong>(E) có tiêu \u0111i\u1ec3m <span class=\"math-tex\">$(0 ; \\sqrt{5})$<\/span> .","<strong>B. <\/strong>(E) có tiêu \u0111i\u1ec3m <span class=\"math-tex\">$(0 ;- \\sqrt{5})$<\/span> .","<strong>C. <\/strong>(E) có tiêu c\u1ef1 <span class=\"math-tex\">$2\\sqrt{5}$<\/span> .","<strong>D. <\/strong>(E) có tiêu c\u1ef1 b\u1eb1ng <span class=\"math-tex\">$\\sqrt{5}$<\/span>."],"correct":"3","level":"1","hint":"","answer":"<p>(E): <span class=\"math-tex\">$\\dfrac{x^2}{9}+\\dfrac{y^2}{4}=1$<\/span> .<\/p><p>Suy ra a = 3, b = 2, c = <span class=\"math-tex\">$\\sqrt{5}$<\/span> .<\/p><p>Tiêu c\u1ef1 c\u1ee7a (E) là 2c = 2<span class=\"math-tex\">$\\sqrt{5}$<\/span> .<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>C. <\/strong>(E) có tiêu c\u1ef1 <span class=\"math-tex\">$2\\sqrt{5}$<\/span> .<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-05-30 06:47:19","option_type":"math","len":0},{"id":"6909","mon_id":"1158767","chapter_id":"1158892","post_id":"6495","question":"<p>Cho elip x² + 3y² = 3. M\u1ec7nh \u0111\u1ec1 nào <strong>sai <\/strong>trong các m\u1ec7nh \u0111\u1ec1 sau?<\/p>","options":["<strong>A. <\/strong>T\u1ed5ng kho\u1ea3ng cách t\u1eeb m\u1ed7i \u0111i\u1ec3m trên elip t\u1edbi hai tiêu \u0111i\u1ec3m b\u1eb1ng 2<span class=\"math-tex\">$\\sqrt{3}$<\/span> .","<strong>B. <\/strong>Tiêu c\u1ef1 b\u1eb1ng 2.","<strong>C.<\/strong>Tiêu c\u1ef1 b\u1eb1ng 2<span class=\"math-tex\">$\\sqrt{2}$<\/span> .","<strong>D.<\/strong> Hai tiêu \u0111i\u1ec3m <span class=\"math-tex\">$F_1(-\\sqrt{2};0)$<\/span> và <span class=\"math-tex\">$F_2(\\sqrt{2};0)$<\/span> ."],"correct":"2","level":"1","hint":"","answer":"<p>(E): x² + 3y² = 3 ⇔ <span class=\"math-tex\">$\\dfrac{x^2}{3}+\\dfrac{y^2}{1}=1$<\/span>.<\/p><p>⇒ <span class=\"math-tex\">$\\begin{cases}a^2=3\\\\b^2=1\\\\c^2=a^2-b^2=2\\end{cases}$<\/span> ⇒ <span class=\"math-tex\">$\\begin{cases}a=\\sqrt{3}\\\\b=1\\\\c=\\sqrt{2}\\end{cases}$<\/span> .<\/p><p>Suy ra tiêu c\u1ef1 b\u1eb1ng 2c = 2<span class=\"math-tex\">$\\sqrt{2}$<\/span> . Do \u0111ó câu sai là câu <strong>B<\/strong>.<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>B. <\/strong>Tiêu c\u1ef1 b\u1eb1ng 2.<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-05-30 08:21:59","option_type":"math","len":0}]}