{"common":{"save":0,"post_id":"6558","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"5960","post_id":"6558","mon_id":"1158921","chapter_id":"1158928","question":"<p>Phân tích \u0111a th\u1ee9c thành nhân t\u1eed x²y – y + 5x + 5 .<\/p>","options":["<strong>A.<\/strong> (x + 1)(xy + y + 5)","<strong>B.<\/strong> (x + 1)(xy – y – 5)","<strong>C.<\/strong> (x – 1)(xy – y + 5)","<strong>D.<\/strong> (x + 1)(xy – y + 5)"],"correct":"4","level":"3","hint":"","answer":"<p>x²y – y + 5x + 5<\/p><p>= (x²y – y) + (5x + 5)<\/p><p>= y(x² – 1) + 5(x + 1)<\/p><p>= y(x – 1)(x + 1) + 5(x + 1)<\/p><p>= (x + 1)[y(x – 1) + 5]<\/p><p>= (x + 1)(xy – y + 5)<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>D.<\/strong> (x + 1)(xy – y + 5).<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-09 04:36:09","option_type":"txt","len":2},{"id":"5988","post_id":"6558","mon_id":"1158921","chapter_id":"1158928","question":"<p>Tìm x bi\u1ebft 4x² – (x + 1)² = 0 .<\/p>","options":["<strong>A.<\/strong> x = 1 ho\u1eb7c x = –3.","<strong>B.<\/strong> x = 1 ho\u1eb7c x = <span class=\"math-tex\">$-\\dfrac{1}{3}$<\/span>.","<strong>C.<\/strong> x = –1 ho\u1eb7c x = <span class=\"math-tex\">$\\dfrac{1}{3}$<\/span>.","<strong>D.<\/strong> x = –1 ho\u1eb7c x = 3."],"correct":"2","level":"3","hint":"","answer":"<p>4x² – (x + 1)² = 0<\/p><p>(2x)² – (x + 1)² = 0<\/p><p>[2x – (x + 1)][2x + (x + 1)] = 0<\/p><p>(2x – x – 1)(2x + x + 1) = 0<\/p><p>(x – 1)(3x + 1) = 0<\/p><p>x – 1 = 0 ho\u1eb7c 3x + 1 = 0<\/p><p>x = 1 ho\u1eb7c 3x = –1<\/p><p>x = 1 ho\u1eb7c x = <span class=\"math-tex\">$-\\dfrac{1}{3}$<\/span><\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>B.<\/strong> x = 1 ho\u1eb7c x = <span class=\"math-tex\">$-\\dfrac{1}{3}$<\/span>.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-17 03:58:10","option_type":"math","len":0},{"id":"5989","post_id":"6558","mon_id":"1158921","chapter_id":"1158928","question":"<p>Tìm giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a bi\u1ec3u th\u1ee9c M = x² – 18x + 91 .<\/p>","options":["<strong>A.<\/strong> 5","<strong>B.<\/strong> 4","<strong>C.<\/strong> 10","<strong>D.<\/strong> 91"],"correct":"3","level":"3","hint":"","answer":"<p>M = x² – 18x + 91<\/p><p>M = x² – 18x + 81 + 10<\/p><p>M = (x² – 18x + 81) + 10<\/p><p>M = (x² – 2.x.9 + 9²) + 10<\/p><p>M = (x – 9)² + 10<\/p><p>Ta có (x – 9)² <span class=\"math-tex\">$\\ge$<\/span> 0 ; v\u1edbi m\u1ecdi x<\/p><p> (x – 9)² + 10 <span class=\"math-tex\">$\\ge$<\/span> 0 + 10 ; v\u1edbi m\u1ecdi x<\/p><p> M <span class=\"math-tex\">$\\ge$<\/span> 10 ; v\u1edbi m\u1ecdi x.<\/p><p>D\u1ea5u "=" x\u1ea3y ra khi x – 9 = 0 hay x = 9.<\/p><p>V\u1eady giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a M là 10, \u0111\u1ea1t \u0111\u01b0\u1ee3c khi x = 9.<\/p><p>\u0110áp án \u0111úng là <span style=\"color:#16a085;\"><strong>C.<\/strong> 10.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-17 04:05:13","option_type":"txt","len":0}]}
