Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
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{"common":{"save":0,"post_id":"7307","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7562","mon_id":"1158767","chapter_id":"1158861","post_id":"7307","question":"<p>Trong m\u1eb7t ph\u1eb3ng t\u1ecda \u0111\u1ed9 Oxy, cho hai \u0111i\u1ec3m A(–2; 4) và B(8; 4). Tìm t\u1ecda \u0111\u1ed9 \u0111i\u1ec3m C thu\u1ed9c tr\u1ee5c hoành sao cho tam giác ABC vuông t\u1ea1i C.<\/p>","options":["<strong>A.<\/strong> C(6; 0)","<strong>B.<\/strong> C(0; 0) ho\u1eb7c C(6; 0)","<strong>C.<\/strong> C(0; 0)","<strong>D.<\/strong> C(–1; 0) ho\u1eb7c C(0; 0)"],"correct":"2","level":"3","hint":"","answer":"<p>Vì C thu\u1ed9c tr\u1ee5c Ox nên C(x; 0) và <span class=\"math-tex\">$\\overrightarrow{CA}=(-2-x;4)$<\/span>, <span class=\"math-tex\">$\\overrightarrow{CB}=(8-x;4)$<\/span>.<\/p><p>\u0110\u1ec3 tam giác ABC vuông t\u1ea1i C thì <span class=\"math-tex\">$\\overrightarrow{CA}.\\overrightarrow{CB}=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$(-2-x)(8-x)+16=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$x^2-6x=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$x=0$<\/span> ho\u1eb7c <span class=\"math-tex\">$x=6$<\/span>.<\/p><p>Khi \u0111ó <span class=\"math-tex\">$C(0;0)$<\/span> ho\u1eb7c <span class=\"math-tex\">$C(6;0)$<\/span>.<\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> C(0; 0) ho\u1eb7c C(6; 0).<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-04-21 01:12:24","option_type":"txt","len":2},{"id":"7563","mon_id":"1158767","chapter_id":"1158861","post_id":"7307","question":"<p>Trong m\u1eb7t ph\u1eb3ng t\u1ecda \u0111\u1ed9 Oxy, cho hai \u0111i\u1ec3m A(1; 2) và B(–3; 1). Tìm t\u1ecda \u0111\u1ed9 \u0111i\u1ec3m C thu\u1ed9c tr\u1ee5c tung sao cho tam giác ABC vuông t\u1ea1i A.<\/p>","options":["<strong>A.<\/strong> C(0; 6)","<strong>B.<\/strong> C(5; 0)","<strong>C.<\/strong> C(3; 1)","<strong>D.<\/strong> C(0; –6)"],"correct":"1","level":"3","hint":"","answer":"<p>Vì C thu\u1ed9c tr\u1ee5c Oy nên C(0; y) và <span class=\"math-tex\">$\\overrightarrow{AB}=(-4;-1)$<\/span>, <span class=\"math-tex\">$\\overrightarrow{AC}=(-1;y-2)$<\/span>.<\/p><p>\u0110\u1ec3 tam giác ABC vuông t\u1ea1i A thì <span class=\"math-tex\">$\\overrightarrow{AB}.\\overrightarrow{AC}=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$4-(y-2)=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$y=6$<\/span><\/p><p>Khi \u0111ó C(0; 6).<\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> C(0; 6).<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-04-21 01:18:07","option_type":"txt","len":2},{"id":"7564","mon_id":"1158767","chapter_id":"1158861","post_id":"7307","question":"<p>Trong m\u1eb7t ph\u1eb3ng t\u1ecda \u0111\u1ed9 Oxy, cho ba \u0111i\u1ec3m A(–4; 0), B(–5; 0) và C(3; 0). Tìm \u0111i\u1ec3m M thu\u1ed9c tr\u1ee5c hoành sao cho <span class=\"math-tex\">$\\overrightarrow{MA}+\\overrightarrow{MB}+\\overrightarrow{MC}=\\overrightarrow{0}$<\/span>.<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$M(-2;0)$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$M(2;0)$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$M(-4;0)$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$M(-5;0)$<\/span>"],"correct":"1","level":"3","hint":"","answer":"<p>Vì M thu\u1ed9c tr\u1ee5c Ox nên M(x; 0).<\/p><p>Ta có <span class=\"math-tex\">$\\overrightarrow{MA}=(-4-x;0)$<\/span>, <span class=\"math-tex\">$\\overrightarrow{MB}=(-5-x;0)$<\/span>, <span class=\"math-tex\">$\\overrightarrow{MC}=(3-x;0)$<\/span>.<\/p><p>Khi \u0111ó <span class=\"math-tex\">$\\overrightarrow{MA}+\\overrightarrow{MB}+\\overrightarrow{MC}=\\overrightarrow{0}$<\/span><\/p><p>⇔ <span class=\"math-tex\">$(-6-3x;0)=(0;0)$<\/span><\/p><p>⇔ <span class=\"math-tex\">$-6-3x=0$<\/span><\/p><p>⇔ <span class=\"math-tex\">$x=-2$<\/span>.<\/p><p>V\u1eady M(–2; 0).<\/p><p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> <span class=\"math-tex\">$M(-2;0)$<\/span>.<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-04-21 01:26:05","option_type":"math","len":0}]}