{"article_info":{"article_id":121147,"cat_id":1090,"cat_title":"SBT Toán 10 - Chân trời sáng tạo","publish_time":1665126180,"cat_id2":1090,"is_link":0,"thumbnail":"","title":"Giải bài 5 trang 9 SBT toán 10 - Chân trời sáng tạo","label":"Bài 5 trang 9 sách bài tập toán 10 - Chân trời sáng tạo","alias":"giai-bai-5-trang-9-sbt-toan-10-chan-troi-sang-tao","introtext":"Xét dấu của các tam thức bậc hai sau:\r\na) \\(f\\left( x \\right) = {x^2} - 5x + 4\\)   \r\nb) \\(f\\left( x \\right) =  - \\frac{1}{3}{x^2} + 2x - 3\\)\r\nc) \\(f\\left( x \\right) = 3{x^2} + 6x + 4\\)","content":"<style>\r\n.method-close-icon{position: relative;float: right;top: 6px;transform: rotate(270deg);-ms-transform:rotate(270deg);-moz-transform:rotate(270deg);-webkit-transform:rotate(270deg);-o-transform:rotate(270deg);}\r\n.method-open-icon{position: relative;float: right;top: 6px;}\r\n</style>\r\n<p><strong style=\"font-size: 16px;\">Đề bài</strong></p><p>Xét dấu của các tam thức bậc hai sau:</p>\r\n<p>a) \\(f\\left( x \\right) = {x^2} - 5x + 4\\)   </p>\r\n<p>b) \\(f\\left( x \\right) =  - \\frac{1}{3}{x^2} + 2x - 3\\)</p>\r\n<p>c) \\(f\\left( x \\right) = 3{x^2} + 6x + 4\\)</p>\r\n<p>d) \\(f\\left( x \\right) =  - 2{x^2} + 3x + 5\\)</p>\r\n<p>e) \\(f\\left( x \\right) =  - 6{x^2} + 3x - 1\\) </p>\r\n<p>g) \\(f\\left( x \\right) = 4{x^2} + 12x + 9\\)</p><div id=\"pos_end_question\"></div><p><strong style=\"font-size: 16px;\">Lời giải chi tiết</strong></p><p class=\"MsoNormal\"><span lang=\"EN-US\">a) \\(f\\left( x \\right) = {x^2} - 5x + 4\\) có \\(\\Delta  = 9 &gt; 0\\) , hai nghiệm phân biết \\({x_1} = 1,{x_2} = 4\\) và có \\(a = 1 &gt; 0\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Ta có bảng xét dấu \\(f\\left( x \\right)\\) như sau:</span></p>\r\n<p class=\"MsoNormal\"><img src=\"https://img.loigiaihay.com/picture/2022/1007/1_1.png\" style=\"width: 100%; max-width: 700px;\" /></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) dương trong hai khoảng \\(\\left( { - \\infty ;1} \\right)\\) và \\(\\left( {4; + \\infty } \\right)\\), âm trong khoảng \\(\\left( {1;4} \\right)\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">b) \\(f\\left( x \\right) =  - \\frac{1}{3}{x^2} + 2x - 3\\) có \\(\\Delta  = 0\\) , có nghiệm kép \\({x_1} = {x_2} = 3\\)và có \\(a =  - \\frac{1}{3} &lt; 0\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) âm với mọi \\(x \\ne 3\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">c) \\(f\\left( x \\right) = 3{x^2} + 6x + 4\\) có \\(\\Delta  =  - 12 &lt; 0\\) và có \\(a = 3 &gt; 0\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) dương với mọi \\(x \\in \\mathbb{R}\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">d) \\(f\\left( x \\right) =  - 2{x^2} + 3x + 5\\) có \\(\\Delta  = 49 &gt; 0\\) , hai nghiệm phân biết \\({x_1} =  - 1,{x_2} = \\frac{5}{2}\\) và có \\(a =  - 2 &lt; 0\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Ta có bảng xét dấu \\(f\\left( x \\right)\\) như sau:</span></p>\r\n<p class=\"MsoNormal\"><img src=\"https://img.loigiaihay.com/picture/2022/1007/2.png\" style=\"width: 100%; max-width: 700px;\" /></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) âm trong khoảng \\(\\left( { - \\infty ; - 1} \\right)\\) và \\(\\left( {\\frac{5}{2}; + \\infty } \\right)\\), dương trong khoảng \\(\\left( { - 1;\\frac{5}{2}} \\right)\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">e) \\(f\\left( x \\right) =  - 6{x^2} + 3x - 1\\) có \\(\\Delta  =  - 15 &lt; 0\\) và có \\(a =  - 6 &lt; 0\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) âm với mọi \\(x \\in \\mathbb{R}\\)</span></p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">g) \\(f\\left( x \\right) = 4{x^2} + 12x + 9\\) có \\(\\Delta  = 0\\) , có nghiệm kép \\({x_1} = {x_2} =  - \\frac{3}{2}\\)và có \\(a = 4 &gt; 0\\)</span></p>\r\n<p> </p>\r\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Vậy \\(f\\left( x \\right)\\) dương với mọi \\(x \\ne  - \\frac{3}{2}\\)</span></p>\r\n<p class=\"MsoNormal\"><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">a) </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) = {x^2} - 5x + 4\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>= 9 &gt; 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> , hai nghiệm phân biết </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\({x_1} = 1,{x_2} = 4\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a = 1 &gt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Ta có bảng xét dấu </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> như sau:</span></sub></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-no-proof: yes;\" lang=\"EN-US\"><!--[if gte vml 1]><v:shapetype id=\"_x0000_t75\" coordsize=\"21600,21600\"\r\n o:spt=\"75\" o:preferrelative=\"t\" path=\"m@4@5l@4@11@9@11@9@5xe\" filled=\"f\"\r\n stroked=\"f\">\r\n <v:stroke joinstyle=\"miter\"/>\r\n <v:formulas>\r\n  <v:f eqn=\"if lineDrawn pixelLineWidth 0\"/>\r\n  <v:f eqn=\"sum @0 1 0\"/>\r\n  <v:f eqn=\"sum 0 0 @1\"/>\r\n  <v:f eqn=\"prod @2 1 2\"/>\r\n  <v:f eqn=\"prod @3 21600 pixelWidth\"/>\r\n  <v:f eqn=\"prod @3 21600 pixelHeight\"/>\r\n  <v:f eqn=\"sum @0 0 1\"/>\r\n  <v:f eqn=\"prod @6 1 2\"/>\r\n  <v:f eqn=\"prod @7 21600 pixelWidth\"/>\r\n  <v:f eqn=\"sum @8 21600 0\"/>\r\n  <v:f eqn=\"prod @7 21600 pixelHeight\"/>\r\n  <v:f eqn=\"sum @10 21600 0\"/>\r\n </v:formulas>\r\n <v:path o:extrusionok=\"f\" gradientshapeok=\"t\" o:connecttype=\"rect\"/>\r\n <o:lock v:ext=\"edit\" aspectratio=\"t\"/>\r\n</v:shapetype><v:shape id=\"image233.png\" o:spid=\"_x0000_i1026\" type=\"#_x0000_t75\"\r\n style='width:468pt;height:102pt;visibility:visible;mso-wrap-style:square'>\r\n <v:imagedata src=\"file:///C:/Users/DELL/AppData/Local/Temp/msohtmlclip1/01/clip_image001.png\"\r\n  o:title=\"\"/>\r\n</v:shape><![endif]--><!--[if !vml]--><img width=\"624\" height=\"136\" src=\"file:///C:/Users/DELL/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg\" v:shapes=\"image233.png\" /><!--[endif]--></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> dương trong hai khoảng </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( { - \\infty ;1} \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( {4; + \\infty } \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">, âm trong khoảng </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( {1;4} \\right)\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">b) </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) =<span style=\"mso-spacerun: yes;\">  </span>- \\frac{1}{3}{x^2} + 2x - 3\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>= 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> , có nghiệm kép </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\({x_1} = {x_2} = 3\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a =<span style=\"mso-spacerun: yes;\">  </span>- \\frac{1}{3} &lt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> âm với mọi </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(x \\ne 3\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">c) </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) = 3{x^2} + 6x + 4\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>=<span style=\"mso-spacerun: yes;\">  </span>- 12 &lt; 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a = 3 &gt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> dương với mọi </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(x \\in \\mathbb{R}\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">d) </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) =<span style=\"mso-spacerun: yes;\">  </span>- 2{x^2} + 3x + 5\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>= 49 &gt; 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> , hai nghiệm phân biết </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\({x_1} =<span style=\"mso-spacerun: yes;\">  </span>- 1,{x_2} = \\frac{5}{2}\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a =<span style=\"mso-spacerun: yes;\">  </span>- 2 &lt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Ta có bảng xét dấu </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> như sau:</span></sub></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-no-proof: yes;\" lang=\"EN-US\"><!--[if gte vml 1]><v:shape id=\"image232.png\" o:spid=\"_x0000_i1025\"\r\n type=\"#_x0000_t75\" style='width:468pt;height:102pt;visibility:visible;\r\n mso-wrap-style:square'>\r\n <v:imagedata src=\"file:///C:/Users/DELL/AppData/Local/Temp/msohtmlclip1/01/clip_image003.png\"\r\n  o:title=\"\"/>\r\n</v:shape><![endif]--><!--[if !vml]--><img width=\"624\" height=\"136\" src=\"file:///C:/Users/DELL/AppData/Local/Temp/msohtmlclip1/01/clip_image004.jpg\" v:shapes=\"image232.png\" /><!--[endif]--></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> âm trong khoảng </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( { - \\infty ; - 1} \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( {\\frac{5}{2}; + \\infty } \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">, dương trong khoảng </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\left( { - 1;\\frac{5}{2}} \\right)\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">e) </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) =<span style=\"mso-spacerun: yes;\">  </span>- 6{x^2} + 3x - 1\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>=<span style=\"mso-spacerun: yes;\">  </span>- 15 &lt; 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a =<span style=\"mso-spacerun: yes;\">  </span>- 6 &lt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> âm với mọi </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(x \\in \\mathbb{R}\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">g) </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right) = 4{x^2} + 12x + 9\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(\\Delta<span style=\"mso-spacerun: yes;\">  </span>= 0\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> , có nghiệm kép </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\({x_1} = {x_2} =<span style=\"mso-spacerun: yes;\">  </span>- \\frac{3}{2}\\)</span></span><sub><span style=\"font-size: 23.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">và có </span></sub><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(a = 4 &gt; 0\\)</span></span></p>\r\n<p class=\"MsoNormal\"><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\">Vậy </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(f\\left( x \\right)\\)</span></span><span style=\"font-size: 14.0pt; line-height: 115%; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman';\" lang=\"EN-US\"> dương với mọi </span><span class=\"MTConvertedEquation\"><span style=\"font-size: 14.0pt; line-height: 115%; mso-fareast-font-family: Calibri;\" lang=\"EN-US\">\\(x \\ne<span style=\"mso-spacerun: yes;\">  </span>- \\frac{3}{2}\\)</span></span></p>\r\n<p> </p>","common_article":"","display_type":1,"vungoi_exam_id":"","article_type":1,"cmt_count":0,"zip_status":1,"last_modified_time":1665127312,"last_zip_time":1665127312,"zip_link":"https://offline.loigiaihay.com/articles/1090/121147/121147_1665127312.zip","picture":"","youtube_id":"","video_start_time":"0","quizlet_id":"0","ref_article_id":0,"readmore_display_type":0,"wiki":0,"comment_url":"https://loigiaihay.com/comment/giai-bai-5-trang-9-sbt-toan-10-chan-troi-sang-tao-c1090a121147.html","origin_url":"https://loigiaihay.com/giai-bai-5-trang-9-sbt-toan-10-chan-troi-sang-tao-c1090a121147.html","relate_link":[]},"callouts":[],"relate_articles":[],"others_in_cat":[{"article_id":121148,"cat_id":1090,"publish_time":1665126900,"is_link":0,"thumbnail":"","title":"Giải bài 6 trang 9 SBT toán 10 - Chân trời sáng tạo","alias":"giai-bai-6-trang-9-sbt-toan-10-chan-troi-sang-tao","introtext":"Tìm các giá trị của tham số m để:\r\na) \\(f\\left( x \\right) = \\left( {m + 1} \\right){x^2} + 5x + 2\\) là tam thức bậc hai không đổi dấu trên \\(\\mathbb{R}\\)","display_type":1,"article_type":1},{"article_id":121149,"cat_id":1090,"publish_time":1665127320,"is_link":0,"thumbnail":"","title":"Giải bài 7 trang 10 SBT toán 10 - Chân trời sáng tạo","alias":"giai-bai-7-trang-10-sbt-toan-10-chan-troi-sang-tao","introtext":"Chứng minh rằng\r\na) \\(2{x^2} + \\sqrt 3 x + 1 > 0\\) với mọi \\(x \\in \\mathbb{R}\\)\r\nb) \\({x^2} + x + \\frac{1}{4} \\ge 0\\) với mọi \\(x \\in \\mathbb{R}\\)\r\nc) \\( - {x^2} <  - 2x + 3\\) với mọi \\(x \\in \\mathbb{R}\\)\r\n","display_type":1,"article_type":1},{"article_id":121151,"cat_id":1090,"publish_time":1665127440,"is_link":0,"thumbnail":"","title":"Giải bài 8 trang 10 SBT toán 10 - Chân trời sáng tạo","alias":"giai-bai-8-trang-10-sbt-toan-10-chan-troi-sang-tao","introtext":"Xác định giá trị của các hệ số a, b, c và xét dấu của tam thức bậc hai \\(f\\left( x \\right) = a{x^2} + bx + c\\) trong mỗi trường hợp sau:\r\na) Đồ thị của hàm số \\(y = f\\left( x \\right)\\) đi qua ba điểm có tọa độ là \\(\\left( { - 1; - 4} \\right),\\left( {0;3} \\right)\\) và \\(\\left( {1; - 14} \\right)\\)","display_type":1,"article_type":1},{"article_id":121146,"cat_id":1090,"publish_time":1665125760,"is_link":0,"thumbnail":"","title":"Giải bài 4 trang 9 SBT toán 10 - Chân trời sáng tạo","alias":"giai-bai-4-trang-9-sbt-toan-10-chan-troi-sang-tao","introtext":"Dựa vào đồ thị của hàm số bậc hai được cho trong hình dưới đây, xét dấu của tam thức bậc hai tương ứng:","display_type":1,"article_type":1},{"article_id":121145,"cat_id":1090,"publish_time":1665125640,"is_link":0,"thumbnail":"","title":"Giải bài 3 trang 9 SBT toán 10 - Chân trời sáng tạo","alias":"giai-bai-3-trang-9-sbt-toan-10-chan-troi-sang-tao","introtext":"Tìm các giá trị của tham số m để:\r\na) \\(f\\left( x \\right) = \\left( {{m^2} + 9} \\right){x^2} + \\left( {m + 6} \\right)x + 1\\) là một tam thức bậc hai có một nghiệm duy nhất\r\nb) \\(f\\left( x \\right) = \\left( {m - 1} \\right){x^2} + 3x + 1\\) là một tam thức bậc hai có hai nghiệm phân biệt\r\nc) \\(f\\left( x \\right) = m{x^2} + \\left( {m + 2} \\right)x + 1\\) là một tam thức bậc hai vô nghiệm\r\n","display_type":1,"article_type":1},{"article_id":121144,"cat_id":1090,"publish_time":1665125520,"is_link":0,"thumbnail":"","title":"Giải bài 2 trang 9 SBT 10 - Chân trời sáng tạo","alias":"giai-bai-2-trang-9-sbt-10-chan-troi-sang-tao","introtext":"Tìm giá trị của tham số m để:\r\na) \\(f\\left( x \\right) = \\left( {2m - 8} \\right){x^2} + 2mx + 1\\) là một tam thức bậc hai\r\nb) \\(f\\left( x \\right) = \\left( {2m + 3} \\right){x^2} + 3x - 4{m^2}\\) là một tam thức bậc hai có \\(x = 3\\) là một nghiệm\r\nc) \\(f\\left( x \\right) = 2{x^2} + mx - 3\\) dương tại \\(x = 2\\)","display_type":1,"article_type":1},{"article_id":121143,"cat_id":1090,"publish_time":1665125640,"is_link":0,"thumbnail":"","title":"Giải bài 1 trang 8 sách bài tập toán 10 tập 2 - Chân trời sáng tạo","alias":"giai-bai-1-trang-8-sach-bai-tap-toan-10-tap-2-chan-troi-sang-tao","introtext":"Tính biệt thức và nghiệm (nếu có) của tam thức bậc hai sau. Xác định dấu của chúng tại (x =  - 2)\r\na) (fleft( x right) =  - 2{x^2} + 3x - 4)\r\nb) (gleft( x right) = 2{x^2} + 8x + 8)\r\nc) (hleft( x right) = 3{x^2} + 7x - 10)\r\n","display_type":1,"article_type":1}],"event_info":{"title":"Bài 1. Dấu của tam thức bậc hai - SBT Toán 10 CTST","cat_id":1090,"alias":"bai-1-dau-cua-tam-thuc-bac-hai-sbt-toan-10-ctst","introtext":"","type":"event","item_id":28543,"item_type":2},"banner":[],"top_banner":"","content_expanded":[],"child_events":[{"id":"28543","title":"Bài 1. Dấu của tam thức bậc hai - SBT Toán 10 CTST","short_title":"Bài 1. Dấu của tam thức bậc hai","alias":"bai-1-dau-cua-tam-thuc-bac-hai-sbt-toan-10-ctst","picture":"","is_link":"0","links":"","is_hot":"0","is_all":"0","category_id":"1090","ordering":"28050","parent_id":"28542"}],"parent_events":[{"id":"28542","title":"Chương VII. Bất phương trình bậc hai một ấn - SBT Toán 10 CTST","short_title":"Chương VII. 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