Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
Bạn hãy xác thực địa chỉ email đăng ký nhé. Chi tiết xem tại đây
Bạn hãy xác thực địa chỉ email đăng ký nhé. Chi tiết xem tại đây
HomeLớp 12Toán lớp 12 - Sách Kết nối tri thứcBài 2. Giá trị lớn nhất và giá trị nhỏ nhất của hàm sốBài tập trung bình
{"common":{"save":0,"post_id":"7510","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"5322","post_id":"7510","mon_id":"1159285","chapter_id":"1159288","question":"<p>Giá tr\u1ecb l\u1edbn nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=-x^4+12x^2+1$<\/span> trên \u0111o\u1ea1n [–1; 2] b\u1eb1ng:<\/p>","options":["<strong>A.<\/strong> 1","<strong>B.<\/strong> 37","<strong>C.<\/strong> 33","<strong>D.<\/strong> 12"],"correct":"3","level":"2","hint":"<p>S\u1eed d\u1ee5ng quy t\u1eafc tìm giá tr\u1ecb l\u1edbn nh\u1ea5t, nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 trên \u0111o\u1ea1n [a; b].<\/p>","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>C.<\/strong> 33<\/span><\/p><p><span class=\"math-tex\">$f(x)=-x^4+12x^2+1$<\/span> liên t\u1ee5c trên \u0111o\u1ea1n [–1; 2] và <span class=\"math-tex\">$f^\\prime(x)=-4x^3+24x$<\/span>.<\/p><p><span class=\"math-tex\">$f^\\prime(x)=0$<\/span> ⇔ <span class=\"math-tex\">$-4x^3+24x=0$<\/span> ⇔ x = 0 ho\u1eb7c x = <span class=\"math-tex\">$\\sqrt{6}$<\/span> (lo\u1ea1i) ho\u1eb7c x = <span class=\"math-tex\">$-\\sqrt{6}$<\/span> (lo\u1ea1i).<\/p><p>Ta có: <span class=\"math-tex\">$f(-1)=12$<\/span>, <span class=\"math-tex\">$f(2)=33$<\/span>, <span class=\"math-tex\">$f(0)=1$<\/span>.<\/p><p>V\u1eady giá tr\u1ecb l\u1edbn nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=-x^4+12x^2+1$<\/span> trên \u0111o\u1ea1n [–1; 2] b\u1eb1ng 33 t\u1ea1i x = 2.<\/p>","type":"choose","extra_type":"shape1","user_id":"131","test":"0","date":"2024-06-16 02:54:27","option_type":"txt","len":0},{"id":"5324","post_id":"7510","mon_id":"1159285","chapter_id":"1159288","question":"<p>Giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=x^3-24x$<\/span> trên \u0111o\u1ea1n [2; 19] b\u1eb1ng<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$-32\\sqrt{2}$<\/span>","<strong>B.<\/strong> –40","<strong>C.<\/strong> <span class=\"math-tex\">$32\\sqrt{2}$<\/span>","<strong>D.<\/strong> –45"],"correct":"1","level":"2","hint":"<p>S\u1eed d\u1ee5ng quy t\u1eafc tìm giá tr\u1ecb l\u1edbn nh\u1ea5t, nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 trên \u0111o\u1ea1n [a; b].<\/p>","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> <span class=\"math-tex\">$-32\\sqrt{2}$<\/span><\/span><\/p><p><span class=\"math-tex\">$f(x)=x^3-24x$<\/span> liên t\u1ee5c trên \u0111o\u1ea1n [2; 19] và <span class=\"math-tex\">$f^\\prime(x)=3x^2-24$<\/span>.<\/p><p><span class=\"math-tex\">$f^\\prime(x)=0$<\/span> ⇔ <span class=\"math-tex\">$3x^2-24=0$<\/span> ⇔ x = <span class=\"math-tex\">$2\\sqrt{2}$<\/span> ∈ [2; 19] ho\u1eb7c x = <span class=\"math-tex\">$-2\\sqrt{2}$<\/span> ∉ [2; 19].<\/p><p>Khi \u0111ó <span class=\"math-tex\">$f(2)=-40$<\/span> ; <span class=\"math-tex\">$f(2\\sqrt{2})=-32\\sqrt{2}$<\/span> ; <span class=\"math-tex\">$f(19)=6403$<\/span>.<\/p><p>V\u1eady giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=x^3-24x$<\/span> trên \u0111o\u1ea1n [2; 19] là <span class=\"math-tex\">$-32\\sqrt{2}$<\/span> t\u1ea1i x = <span class=\"math-tex\">$2\\sqrt{2}$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-06-16 02:59:03","option_type":"math","len":0},{"id":"5326","post_id":"7510","mon_id":"1159285","chapter_id":"1159288","question":"<p>Giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=x^3-3x+2$<\/span> trên \u0111o\u1ea1n [–3; 3] b\u1eb1ng<\/p>","options":["<strong>A.<\/strong> 0","<strong>B.<\/strong> –16","<strong>C.<\/strong> 20","<strong>D.<\/strong> 4"],"correct":"2","level":"2","hint":"<p>S\u1eed d\u1ee5ng quy t\u1eafc tìm giá tr\u1ecb l\u1edbn nh\u1ea5t, nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 trên \u0111o\u1ea1n [a; b].<\/p>","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> –16<\/span><\/p><p> <span class=\"math-tex\">$f(x)=x^3-3x+2$<\/span> liên t\u1ee5c trên \u0111o\u1ea1n [–3; 3] và <span class=\"math-tex\">$f^\\prime(x)=3x^2-3$<\/span>.<\/p><p><span class=\"math-tex\">$f^\\prime(x)=0$<\/span> ⇔ <span class=\"math-tex\">$3x^2-3=0$<\/span> ⇔ x = <span class=\"math-tex\">$\\pm$<\/span>1 ∈ [–3; 3].<\/p><p>Khi \u0111ó <span class=\"math-tex\">$f(-3)=-16$<\/span> ; <span class=\"math-tex\">$f(-1)=4$<\/span> ; <span class=\"math-tex\">$f(1)=0$<\/span> ; <span class=\"math-tex\">$f(3)=20$<\/span>.<\/p><p>V\u1eady giá tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a hàm s\u1ed1 <span class=\"math-tex\">$f(x)=x^3-3x+2$<\/span> trên \u0111o\u1ea1n [–3; 3] b\u1eb1ng –16 t\u1ea1i x = –3.<\/p>","type":"choose","extra_type":"shape2","user_id":"131","test":"0","date":"2024-06-16 03:11:15","option_type":"txt","len":0}]}