Ứng dụng đạo hàm để giải quyết một số vấn đề liên quan đến thực tiễn

Home Lớp 12 Toán lớp 12 - Sách Kết nối tri thức Bài 5. Ứng dụng đạo hàm để giải quyết một số vấn đề liên quan đến thực tiễn.Bài tập nâng cao

{"common":{"save":0,"post_id":"7547","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"5490","post_id":"7547","mon_id":"1159285","chapter_id":"1159288","question":"M\u1ed9t x\u01b0\u1edfng in có 15 máy in \u0111\u01b0\u1ee3c cài \u0111\u1eb7t t\u1ef1 \u0111\u1ed9ng và giám sát b\u1edfi m\u1ed9t k\u1ef9 s\u01b0, m\u1ed7i máy in có th\u1ec3 in \u0111\u01b0\u1ee3c 30 \u1ea5n ph\u1ea9m trong 1 gi\u1edd, chi phí cài \u0111\u1eb7t và b\u1ea3o d\u01b0\u1ee1ng cho m\u1ed7i máy in cho 1 \u0111\u1ee3t hàng là 48000 \u0111\u1ed3ng, chi phí tr\u1ea3 cho k\u1ef9 s\u01b0 giám sát là 24000 \u0111\u1ed3ng\/gi\u1edd. \u0110\u1ee3t hàng này x\u01b0\u1edfng in nh\u1eadn 6000 \u1ea5n ph\u1ea9m thì s\u1ed1 máy in c\u1ea7n s\u1eed d\u1ee5ng \u0111\u1ec3 chi phí in ít nh\u1ea5t là<\/span><\/p>","options":["A.<\/strong> 10 máy","B.<\/strong> 11 máy","C.<\/strong> 12 máy","D.<\/strong> 9 máy"],"correct":"1","level":"3","hint":"S\u1eed d\u1ee5ng GTNN c\u1ee7a hàm s\u1ed1.<\/p>","answer":"Ch\u1ecdn A.<\/strong> 10 máy<\/span><\/p>G\u1ecdi x (0 < x < 15) là s\u1ed1 máy in c\u1ea7n s\u1eed d\u1ee5ng \u0111\u1ec3 in lô hàng.<\/p>Chi phí cài \u0111\u1eb7t và b\u1ea3o d\u01b0\u1ee1ng là 48000x.<\/p>S\u1ed1 gi\u1edd in h\u1ebft s\u1ed1 \u1ea5n ph\u1ea9m là $\\dfrac{6000}{30x}$<\/span>, chi phí giám sát là $\\dfrac{6000}{30x}.24000=\\dfrac{4800000}{x}$<\/span>.<\/p>T\u1ed5ng chi phí in là $P(x)=48000x+\\dfrac{4800000}{x}$<\/span>.<\/p>$P^\\prime(x)=48000-\\dfrac{4800000}{x^2}$<\/span>; $P^\\prime(x)=0$<\/span> ⇔ $x^2-100=0$<\/span> ⇔ x = 10 ho\u1eb7c x = –10 (lo\u1ea1i).<\/p>B\u1ea3ng bi\u1ebfn thiên:<\/p><svg height=\"170\" width=\"300\"> <g> <title><\/title> <rect fill=\"#fff\" height=\"172\" id=\"canvas_background\" width=\"302\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" height=\"100%\" id=\"canvasGrid\" overflow=\"visible\" width=\"100%\" x=\"0\" y=\"0\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g> <title><\/title> <g id=\"svg_20\"> <line fill=\"none\" id=\"svg_1\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"-1.7\" x2=\"299.29999\" y1=\"29.65\" y2=\"29.65\"><\/line> <line fill=\"none\" id=\"svg_2\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"-0.7\" x2=\"300.29999\" y1=\"65.65\" y2=\"65.65\"><\/line> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_3\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"53.3\" x2=\"53\" y1=\"-1.35\" y2=\"169.64999\"><\/line> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"21.3\" xml:space=\"preserve\" y=\"20.65\">x<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"4.3\" xml:space=\"preserve\" y=\"57.65\">P'(x)<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"3.3\" xml:space=\"preserve\" y=\"117.64999\">P(x)<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"58.3\" xml:space=\"preserve\" y=\"21.65\">0<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"157.29999\" xml:space=\"preserve\" y=\"22.65\">10<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"275.29999\" xml:space=\"preserve\" y=\"22.65\">15<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"164.29999\" xml:space=\"preserve\" y=\"55.65\">0<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(2.6259796619415283,0,0,1,-141.94801704435122,0) \" x=\"93.01215\" xml:space=\"preserve\" y=\"54.65\">-<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"214.29999\" xml:space=\"preserve\" y=\"55.65\">+<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_13\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.8652714134561418,0,0,1,18.661878631319222,0) \" x=\"148.81778\" xml:space=\"preserve\" y=\"154.64999\">P(10)<\/text> <g id=\"svg_16\" transform=\"rotate(35.37664794921875 104.14373779296876,114.25000000000001) \"> <line fill=\"#ff0000\" fill-opacity=\"null\" id=\"svg_14\" stroke=\"#ff0000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"53.29999\" x2=\"151.29999\" y1=\"113.65\" y2=\"113.65\"><\/line> <text fill=\"#ff0000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-weight=\"bold\" id=\"svg_15\" stroke=\"#ff0000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"141.29999\" xml:space=\"preserve\" y=\"122.65\">><\/text> <\/g> <g id=\"svg_19\" transform=\"rotate(-38.59939956665039 239.1437377929687,113.25) \"> <line fill=\"#ff0000\" fill-opacity=\"null\" id=\"svg_17\" stroke=\"#ff0000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"188.29999\" x2=\"286.29999\" y1=\"112.65\" y2=\"112.65\"><\/line> <text fill=\"#ff0000\" fill-opacity=\"null\" font-family=\"Times New Roman, Times, serif\" font-size=\"24\" font-weight=\"bold\" id=\"svg_18\" stroke=\"#ff0000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"276.29999\" xml:space=\"preserve\" y=\"121.65\">><\/text> <\/g> <\/g> <\/g> <\/svg><\/span><\/p>V\u1eady chi phí in nh\u1ecf nh\u1ea5t là 10 máy.<\/p>","type":"choose","extra_type":"shape1","user_id":"131","test":"0","date":"2024-08-04 03:26:49","option_type":"txt","len":0},{"id":"5492","post_id":"7547","mon_id":"1159285","chapter_id":"1159288","question":"M\u1ed9t ch\u1ea5t \u0111i\u1ec3m chuy\u1ec3n \u0111\u1ed9ng th\u1eb3ng v\u1edbi quãng \u0111\u01b0\u1eddng bi\u1ebfn thiên theo th\u1eddi gian b\u1edfi quy lu\u1eadt $s(t)=t^3-4t^2+12$<\/span> (m), trong \u0111ó t (s) là kho\u1ea3ng th\u1eddi gian tính t\u1eeb lúc b\u1eaft \u0111\u1ea7u chuy\u1ec3n \u0111\u1ed9ng. V\u1eadn t\u1ed1c c\u1ee7a ch\u1ea5t \u0111i\u1ec3m \u0111ó \u0111\u1ea1t giá tr\u1ecb bé nh\u1ea5t khi t b\u1eb1ng bao nhiêu?<\/span><\/p>","options":["A.<\/strong> 2s","B.<\/strong> $\\dfrac{8}{3}$<\/span>s","C.<\/strong> 0s","D.<\/strong> $\\dfrac{4}{3}$<\/span>s"],"correct":"4","level":"3","hint":"S\u1eed d\u1ee5ng ý ngh\u0129a c\u01a1 h\u1ecdc c\u1ee7a \u0111\u1ea1o hàm và GTNN c\u1ee7a hàm s\u1ed1.<\/p>","answer":"Ch\u1ecdn D.<\/strong> $\\dfrac{4}{3}$<\/span>s<\/span><\/p>$v(t)=s^\\prime(t)=3t^2-8t$<\/span><\/p>$v^\\prime(t)=6t-8$<\/span>. Khi \u0111ó $v^\\prime(t)=0\\Leftrightarrow 6t-8=0$<\/span> ⇔ $t=\\dfrac{4}{3}$<\/span>.<\/p><svg height=\"190\" width=\"300\"> <g><title><\/title><rect fill=\"#fff\" height=\"192\" id=\"canvas_background\" width=\"302\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" id=\"canvasGrid\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" id=\"svg_14\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g><title><\/title><line fill=\"none\" id=\"svg_1\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"34.3\" x2=\"34\" y1=\"-0.35\" y2=\"187.64999\"><\/line> <line fill=\"none\" id=\"svg_2\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"-3.7\" x2=\"301.29999\" y1=\"52\" y2=\"51.65\"><\/line> <line fill=\"none\" id=\"svg_3\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"-3.7\" x2=\"301.29999\" y1=\"87\" y2=\"86.65\"><\/line> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_4\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"11.3\" xml:space=\"preserve\" y=\"34.65\">t<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_5\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"7.3\" xml:space=\"preserve\" y=\"73.65\">v'<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" font-style=\"italic\" id=\"svg_6\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"10.3\" xml:space=\"preserve\" y=\"141.64999\">v<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" id=\"svg_7\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"40.3\" xml:space=\"preserve\" y=\"35.65\">0<\/text> <g id=\"svg_10\"> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" id=\"svg_8\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"263.29999\" xml:space=\"preserve\" y=\"35.65\">+<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" id=\"svg_9\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-90 287.30001831054693,26.24999618530271) \" x=\"281.29999\" xml:space=\"preserve\" y=\"34.65\">8<\/text> <\/g> <g id=\"svg_15\"> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_11\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"169.29999\" xml:space=\"preserve\" y=\"17.65\">4<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_12\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"169.29999\" xml:space=\"preserve\" y=\"42.65\">3<\/text> <line fill=\"none\" id=\"svg_13\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"164.29999\" x2=\"184.29999\" y1=\"23.65\" y2=\"23.65\"><\/line> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_21\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"167.29999\" xml:space=\"preserve\" y=\"76.65\">0<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" id=\"svg_22\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.750604271888733,0,0,1,-68.53016658744764,0) \" x=\"94.15615\" xml:space=\"preserve\" y=\"76.65\">-<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" id=\"svg_23\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"218.29999\" xml:space=\"preserve\" y=\"75.65\">+<\/text> <g id=\"svg_26\" stroke=\"null\" transform=\"rotate(31.277589797973633 97.0010147094727,136.11358642578122) \"> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" font-weight=\"bold\" id=\"svg_24\" stroke=\"#ff0000\" stroke-opacity=\"null\" stroke-width=\"1.5\" text-anchor=\"start\" transform=\"matrix(1.3464041948318481,0,0,1,-24.352215953820632,0) \" x=\"117.54822\" xml:space=\"preserve\" y=\"144.20858\">><\/text> <line fill=\"none\" id=\"svg_25\" stroke=\"#ff0000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-width=\"1.5\" x1=\"150.07205\" x2=\"41.01332\" y1=\"136.20858\" y2=\"136.20858\"><\/line> <\/g> <g id=\"svg_28\" stroke=\"null\" transform=\"rotate(-31.52953338623047 241.00100708007818,133.11358642578122) \"> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"24\" font-weight=\"bold\" id=\"svg_19\" stroke=\"#ff0000\" stroke-opacity=\"null\" stroke-width=\"1.5\" text-anchor=\"start\" transform=\"matrix(1.3464041948318481,0,0,1,-24.352215953820632,0) \" x=\"224.49976\" xml:space=\"preserve\" y=\"141.20858\">><\/text> <line fill=\"none\" id=\"svg_27\" stroke=\"#ff0000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-width=\"1.5\" x1=\"294.07205\" x2=\"185.01332\" y1=\"133.20858\" y2=\"133.20858\"><\/line> <\/g> <g id=\"svg_29\"> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_16\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"165.29999\" xml:space=\"preserve\" y=\"160.65\">16<\/text> <text fill=\"#000000\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_17\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" x=\"171.29999\" xml:space=\"preserve\" y=\"185.65\">3<\/text> <line fill=\"none\" id=\"svg_18\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" x1=\"166.29999\" x2=\"186.29999\" y1=\"166.65\" y2=\"166.65\"><\/line> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"’Times New Roman’, Times, serif\" font-size=\"20\" id=\"svg_20\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(2.2001631259918213,0,0,1,-169.58303505221556,0) \" x=\"144.02707\" xml:space=\"preserve\" y=\"172.64999\">-<\/text> <\/g> <\/g> <\/svg><\/span><\/p>D\u1ef1a vào b\u1ea3ng bi\u1ebfn thiên ta có $\\displaystyle\\min_{[0;+\\infty)}v=v\\bigg(\\dfrac{4}{3}\\bigg)=-\\dfrac{16}{3}$<\/span><\/p>V\u1eady v\u1eadn t\u1ed1c c\u1ee7a ch\u1ea5t \u0111i\u1ec3m \u0111ó \u0111\u1ea1t giá tr\u1ecb bé nh\u1ea5t khi $t=\\dfrac{4}{3}$<\/span>.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-08-04 03:33:59","option_type":"math","len":0},{"id":"5494","post_id":"7547","mon_id":"1159285","chapter_id":"1159288","question":"M\u1ed9t ng\u01b0\u1eddi th\u1ee3 c\u1ea7n thi\u1ebft k\u1ebf m\u1ed9t b\u1ec3 cá hình h\u1ed9p ch\u1eef nh\u1eadt b\u1eb1ng kính, có chi\u1ec1u cao là 0,8m, th\u1ec3 tích 576 dm³. Bi\u1ebft ph\u1ea7n n\u1eafp phía trên c\u1ee7a b\u1ec3 cá ng\u01b0\u1eddi th\u1ee3 \u0111ó \u0111\u1ec3 tr\u1ed1ng m\u1ed9t ô có di\u1ec7n tích b\u1eb1ng 30% di\u1ec7n tích \u0111áy b\u1ec3. Bi\u1ebft lo\u1ea1i kính mà ng\u01b0\u1eddi th\u1ee3 s\u1eed d\u1ee5ng làm m\u1eb7t bên và n\u1eafp b\u1ec3 có giá thành 1 000 000 \u0111\u1ed3ng\/m² và kính \u0111\u1ec3 làm m\u1eb7t \u0111áy có giá thành 1 200 000  \u0111\u1ed3ng\/m². Gi\u1ea3 s\u1eed ph\u1ea7n ti\u1ebfp xúc gi\u1eefa các m\u1eb7t là không \u0111áng k\u1ec3. S\u1ed1 ti\u1ec1n mua kính ít nh\u1ea5t \u0111\u1ec3 hoàn thành b\u1ec3 cá g\u1ea7n nh\u1ea5t v\u1edbi s\u1ed1 ti\u1ec1n nào d\u01b0\u1edbi \u0111ây?<\/p>","options":["A.<\/strong> 4,1 tri\u1ec7u \u0111\u1ed3ng","B.<\/strong> 3,2 tri\u1ec7u \u0111\u1ed3ng","C.<\/strong> 2,8 tri\u1ec7u \u0111\u1ed3ng","D.<\/strong> 3,8 tri\u1ec7u \u0111\u1ed3ng"],"correct":"1","level":"3","hint":"S\u1eed d\u1ee5ng công th\u1ee9c tính th\u1ec3 tích hình h\u1ed9p ch\u1eef nh\u1eadt và GTNN c\u1ee7a hàm s\u1ed1. <\/p>","answer":"Ch\u1ecdn A.<\/strong> 4,1 tri\u1ec7u \u0111\u1ed3ng.<\/span><\/p>\u0110\u1eb7t x, y (m) v\u1edbi x, y > 0 l\u1ea7n l\u01b0\u1ee3t là chi\u1ec1u dài và chi\u1ec1u r\u1ed9ng c\u1ee7a \u0111áy b\u1ec3 cá.<\/p>Ta có V = xyh = 0,8xy = 0,576 m³ ⇒ y = $\\dfrac{18}{25x}$<\/span> m.<\/p>S\u1ed1 ti\u1ec1n c\u1ea7n \u0111\u1ec3 mua kính là $\\bigg[2.0,8.(x+y)+\\dfrac{70}{100}xy\\bigg].1+xy.1,2$<\/span><\/p>= $1,6x+\\dfrac{144}{125x}+\\dfrac{171}{125}=f(x)$<\/span> (tri\u1ec7u \u0111\u1ed3ng).<\/p>Ta có $f^\\prime(x)=1,6-\\dfrac{144}{125x^2}=\\dfrac{200x^2-144}{125x^2}$<\/span>.<\/p>$f^\\prime(x)=0$<\/span> ⇔ x = $\\dfrac{3\\sqrt{2}}{5}$<\/span> (m).<\/p>L\u1eadp BBT c\u1ee7a hàm s\u1ed1 f(x) ta th\u1ea5y $\\displaystyle\\min f(x)=f\\bigg(\\dfrac{3\\sqrt{2}}{5}\\bigg)$<\/span> $\\approx$<\/span> 4,1 tri\u1ec7u \u0111\u1ed3ng.<\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2024-08-04 04:01:13","option_type":"txt","len":2}]}