{"common":{"save":0,"post_id":"7752","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7099","post_id":"7752","mon_id":"1159278","chapter_id":"1159281","question":"<p>Giá tr\u1ecb nào c\u1ee7a m d\u01b0\u1edbi \u0111ây \u0111\u1ec3 \u0111i\u1ec3m (2 ; 1) thu\u1ed9c \u0111\u01b0\u1eddng th\u1eb3ng (d): mx –3y = 5?<\/p>","options":["<strong>A.<\/strong> –3","<strong>B.<\/strong> 3","<strong>C.<\/strong> 5","<strong>D.<\/strong> 4"],"correct":"4","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D.<\/strong> 4.<\/span><\/p><p>\u0110i\u1ec3m (2 ; 1) thu\u1ed9c \u0111\u01b0\u1eddng th\u1eb3ng (d) khi và ch\u1ec9 khi (2 ; 1) là nghi\u1ec7m là ph\u01b0\u01a1ng trình <span class=\"math-tex\">$mx-3y=5$<\/span>.<\/p><p>Khi \u0111ó <span class=\"math-tex\">$m.2-3.1=5$<\/span> hay m = 4.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-02 03:27:08","option_type":"txt","len":1},{"id":"7131","post_id":"7752","mon_id":"1159278","chapter_id":"1159281","question":"<p>Bi\u1ebft (a ; b) là nghi\u1ec7m c\u1ee7a h\u1ec7 ph\u01b0\u01a1ng trình <span class=\"math-tex\">$\\begin{cases}4x-3y=2\\\\x+y=4\\end{cases}$<\/span>. Khi \u0111ó giá tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c <span class=\"math-tex\">$2a^2-b^2$<\/span> là<\/p>","options":["<strong>A.<\/strong> 4","<strong>B.<\/strong> 12","<strong>C.<\/strong> 5","<strong>D.<\/strong> 1"],"correct":"1","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> 4.<\/span><\/p><p>Nhân hai v\u1ebf c\u1ee7a ph\u01b0\u01a1ng trình th\u1ee9 hai v\u1edbi 3 ta \u0111\u01b0\u1ee3c: <span class=\"math-tex\">$\\begin{cases}4x-3y=2\\\\3x+3y=12\\end{cases}$<\/span>.<\/p><p>C\u1ed9ng t\u1eebng v\u1ebf hai ph\u01b0\u01a1ng trình c\u1ee7a h\u1ec7 m\u1edbi ta \u0111\u01b0\u1ee3c 7x = 14, suy ra x = 2.<br \/>Th\u1ebf x = 2 vào ph\u01b0\u01a1ng trình th\u1ee9 hai ta \u0111\u01b0\u1ee3c 2 + y = 4, suy ra y = 2.<br \/>V\u1eady h\u1ec7 ph\u01b0\u01a1ng trình \u0111ã cho có nghi\u1ec7m (2 ; 2).<br \/>Khi \u0111ó a = 2; b = 2 suy ra <span class=\"math-tex\">$2a^2-b^2=2.2^2-2^2=4$<\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-03 00:44:16","option_type":"txt","len":0},{"id":"7132","post_id":"7752","mon_id":"1159278","chapter_id":"1159281","question":"<p>V\u1edbi giá tr\u1ecb nào c\u1ee7a m d\u01b0\u1edbi \u0111ây thì \u0111\u01b0\u1eddng th\u1eb3ng <span class=\"math-tex\">$y=(2-m)x+3m-5$<\/span> \u0111i qua \u0111i\u1ec3m (–2 ; 1)?<\/p>","options":["<strong>A.<\/strong> 0","<strong>B.<\/strong> 3","<strong>C.<\/strong> 2","<strong>D.<\/strong> 4"],"correct":"3","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> 2.<\/span><\/p><p>\u0110\u01b0\u1eddng th\u1eb3ng <span class=\"math-tex\">$y=(2-m)x+3m-5$<\/span> \u0111i qua \u0111i\u1ec3m (–2 ; 1) khi và ch\u1ec9 khi (–2 ; 1) là nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng trình <span class=\"math-tex\">$y=(2-m)x+3m-5$<\/span>.<\/p><p>Thay x = –2; y = 1 ta \u0111\u01b0\u1ee3c: <span class=\"math-tex\">$1=(2-m).(-2)+3m-5$<\/span>, suy ra m = 2.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-03 00:48:25","option_type":"txt","len":0}]}
