{"common":{"save":0,"post_id":"6722","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7452","mon_id":"1158767","chapter_id":"1158892","post_id":"6722","question":"<p>T\u1ecda \u0111\u1ed9 tâm I và bán kính R c\u1ee7a \u0111\u01b0\u1eddng tròn (C): <span class=\"math-tex\">$(x+1)^2+(y-3)^2=16$<\/span> là:<\/p>","options":["<strong>A.<\/strong> I(–1; –3) và R = 4","<strong>B.<\/strong> I(–1; 3) và R = 4","<strong>C.<\/strong> I(1; 3) và R = 8","<strong>D.<\/strong> I(–1; 3) và R = 16"],"correct":"2","level":"3","hint":"","answer":"<p>\u0110\u01b0\u1eddng tròn (C): <span class=\"math-tex\">$(x+1)^2+(y-3)^2=16$<\/span> có tâm I(–1; 3) và bán kính R = <span class=\"math-tex\">$\\sqrt{16}=4$<\/span>.<\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> I(–1; 3) và R = 4<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-10-02 21:29:10","option_type":"txt","len":2},{"id":"7454","mon_id":"1158767","chapter_id":"1158892","post_id":"6722","question":"<p>\u0110\u01b0\u1eddng tròn (C): <span class=\"math-tex\">$x^2+y^2-12x+14y+4=0$<\/span> có d\u1ea1ng t\u1ed5ng quát là:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$(x-6)^2+(y+7)^2=89$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$(x+6)^2+(y+7)^2=9$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$(x-6)^2+(y+7)^2=81$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$(x-6)^2+(y-7)^2=81$<\/span>"],"correct":"3","level":"3","hint":"","answer":"<p>\u0110\u01b0\u1eddng tròn (C): <span class=\"math-tex\">$x^2+y^2-12x+14y+4=0$<\/span> có d\u1ea1ng t\u1ed5ng quát là:<\/p><p><span class=\"math-tex\">$(x-6)^2+(y+7)^2=81$<\/span><\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> <span class=\"math-tex\">$(x-6)^2+(y+7)^2=81$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-10-02 21:33:56","option_type":"math","len":0},{"id":"7456","mon_id":"1158767","chapter_id":"1158892","post_id":"6722","question":"<p>\u0110\u01b0\u1eddng tròn (C) \u0111i qua ba \u0111i\u1ec3m A(–3; –1), B(–1; 3) và C(–2; 2) có ph\u01b0\u01a1ng trình là:<\/p>","options":["<strong>A. <\/strong><span class=\"math-tex\">$x^2+y^2+4x+2y-20=0$<\/span>","<strong>B. <\/strong><span class=\"math-tex\">$x^2+y^2+4x+2y+20=0$<\/span>","<strong>C. <\/strong><span class=\"math-tex\">$x^2+y^2-4x-2y-20=0$<\/span>","<strong>D. <\/strong><span class=\"math-tex\">$x^2+y^2-4x+2y-20=0$<\/span>"],"correct":"4","level":"3","hint":"","answer":"<p>G\u1ecdi ph\u01b0\u01a1ng trình \u0111\u01b0\u1eddng tròn (C) là: <span class=\"math-tex\">$x^2+y^2+2ax+2by+c=0$<\/span><\/p><p>Vì \u0111\u01b0\u1eddng tròn (C) \u0111i qua ba \u0111i\u1ec3m A(–3; –1), B(–1; 3) và C(–2; 2) nên ta có:<\/p><p><span class=\"math-tex\">$\\begin{cases}-6a-2b+c=-10\\\\-2a+6b+c=-10\\\\-4a+4b+c=-8\\end{cases}$<\/span> <span class=\"math-tex\">$\\Leftrightarrow \\begin{cases}a=-2\\\\b=1\\\\c=-20\\end{cases}$<\/span><\/p><p>Suy ra (C): <span class=\"math-tex\">$x^2+y^2-4x+2y-20=0$<\/span><\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D. <\/strong><span class=\"math-tex\">$x^2+y^2-4x+2y-20=0$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-10-02 21:42:38","option_type":"math","len":0}]}