HUONG DAN QUAN L i s a DUNG
sir mmi niimui'mns siimvuviu} vAo itAi TOAIV
Tbi uiA Till tm iviiilT, iiiA Till mi6 \IIAT CAA HAM H6 UAC ILII
Trong chuong trinh Dai sd 10, hgc sinh (HS) c6 djp lam quen vdi ham so bdc nhat vd hdm sd bdc hai.
Dac bipt Id hdm sd bgc hai y=f(x)=ax~+bx+c. (a?K)), ling dyng ciia chung vdo edc bdi toan tim gid tri Idn nhat, gia tri nhd nhdt (GTLN, GTNN) thgt phong phii. Trong bdi bdo ndy, tdi xin trinh bdy mpt ling dyng ciia Geometer's Sketchpad (GSP) vdo vipe tim GTLN, GTNN ciia hdm sd bac hai tren mpt doan cho trude.
Bai todn: Tim GTLN^
GTNN eiia ham sd y^f(x)^ax--\-bx+c, (a^O) tren doan [m;n].
Cach giai.
Ta lap Bdng bien thien (BBT) cho hdm sd y=J[x) tren doan [m;n].
Cach gidi nay_ khdng phdi HS ndo ciing de ddng hieu dugc, vi cdc em mdi lam quen vdi Bdng bien thien, md chi xet tren (-x; +00) mgt cdch hinh thirc (?!). Do do, tdi da su dung Geometer's Sketchpad de giiip cdc em nhin nhdn vdn de mgt each trye quan nhdt.
Vi dy. Tim gia tri Idn nhat_, gid tri nhd nhdt cua hdm sd y=f(x)=x^-2x-4 tren doan
[-2;5]..
Mudn gidi dugc bai todn ndy tren phdn mim Geometer's Sketchpad (phien bdn GSP5 hogc GSP4, gido vien cd the tim tren mang, hogc ed the tai vl theo dia chi sau http://wTvw.mediafire.
cm/?ed41khaj5m8qkwm, lira
Phan Van Phirong Truang THPT B Hdi Hgu, Nam Dinh y day la phan mem thuong
mai, neu khdng mua thi chi dung cho myc dich gido dye), Chiing ta can phdi ldm lan lugt cac budc sau:
Budc 1. Tgo mgt bdn ve (sketch) mdi bang each chgn File-> New Sketch (hogc bam to hgp phim tdt Ctri + N).
Budc 2. Chgn Graph->
Show Gird de nhin thdy hp tryc tpa dp.
Budc 3. Ve do thj hdm sd y=J{x)=x'-3x-4 bang each chgn Graph-^FIot New Function...hoac an to hgp phim tat Ctrl+G. Sau dd nhap vao xf'l-lx-A. An OK.
De dl chuyen dd thi den vj tri thich hgp cd the nhdn vd giii chudt trai vdo gdc tga do rdi di chuyen den vi tri mdi.
Budc4. Chgn cdng cy Point Tool (hinh dau cham) Xem hinh I.
- Bdm chpn hai diem -2 vd 5 viia tgo tren true Ox, dn Chi + K de hipn ten cho 2 diem nay, mgc dinh Id A, B (Khi mpt ddi tugng dugc chgn, chiirig se hi bao phii bdi dudng vien mdu hdng).
- Chgn Contruct->Segmeiit de tao doan thang AB (hoac dn Chi + L)
Budc 5. Chgn cdng cu Point Tool. Bam vdo mpt vi tri bat ki tren dogn AB de tap diem C (dn Ctri + K de hipn ten cho diem mdi tgo ndy)..
Chgn cdng cu Translation Arrow Tool. Bam chgn diem C (neu diem C da dugc chpn san thi thdi) vd tryc Ox hoac doan AB.
Chgn ontruct->Peipaidkuhr de dung dudng thdng y di qua C vd vudng gdc vdi AB.
Bam chgn giao diem ciia dudng thang j vd Parabol.
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- Bam vao diem -2 va 5 tren Bam Ctrl + K se hien ten diSm true Ox si tjo hai dijm co tga nay la D (Xem hmh 2).
dp A (-2;0) va B (5;0). (B6 tao dilm D co th6 chon -ChpncongcvTranslation duong thingj va Parabol rbi Arrow Tool (hinh mui ten), jn Ctrl + Shift+ 1).
hoac an ESC. Chpn didm D va duong
Ngay nhan bai 19/6/2012. Ngay duy^l ding 27/7/2012 3 8 . TAP CHI THlflBIGUO DUC-SO 84-8/2012
HUONG DAN QUAN LI SI/DUNG
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thang j hogc tryc Oy. Chgn ontruct->Perpendicular de dung dudng thang k di qua D vd vudng gdc vdiy.
Bam vdo gigo diem cua k yd trye Oy de tao diem E, (bdm Chi +K de hien ten eua diem ndy).
Budc 6. Bam chudt phdi vao diem E, chgn Trace Intersection.
, Chpn dudng, thang j vd k.
Bam Ctrl + H de dn hai dudng thang da chgn.
Chgn diem E, D. Bdm Ctri + L.
Chgn dilm D, C. Bdm Ctri + L.
Chgn 3 doan thdng AB, CD vd DE. Chgn menu Display->Line Styie->Thin.
Chon menu Display->Line S t y l e ^ D a s h e d .
Chon tat cd cdc diem A,B,C,D,E. Bdm Ctrl + K d l an ten cdc diem tren.
_ Budc 7. Bam chudt phdi vdo diem C, chgn Animate Point.
Khi dd hop dieu, khien Motion Controller xuat hien.
Cd the chgn Speed (tdc do khodng 0.50) de dilm E tao vet khi chuyen ddng dugc ro hem.
Liic ndy ta thay khi dilm C di chuyen hong pham vi tir -2 din 5 thi diem D di ehuyen tren Parabol vd cd tung dg thay ddi trong phgm vi tir -5 den 11. Tuong ling vdi GTLN ciia hdm so y^J{x)=x^-2x-4 la II vd GTNN Id-5.
Cd the xem tun^ dg diem D thay_ ddi nhu the ndo bdng cdch bdm chudt phdi vao diem D, chgn Ordinate (y).
(De cira sd nhin rdng hon, cd the chon Display->Hide Text Palette).
Tdi ti^u tham khao Phan trg giiip (Help) ciia phan mem Geometer's Sketchpad 5.
Sumary
This article guides the Geometer's Sketchpad you use to illustrate finding the maximum value, minimum value of quadratic functions y=f(x)=ax^+bx+c, (a?^) m the showed range. By showing students see the value of the fiinction changes when the number of variations on a given segment defined.
PHUONG P H A P S U D U N G ATLAT DIA LI., ...luge dd vdi bdn do de khai
thdc kiln thiie.
+ Sir dyng cau hdi yeu cau HS phdn tich Idt cdt dia hinh, hogc dya vdo bdn dd, ve vd phan tich lat cat dia hinh.
(Cac cdeh ldm tren cd the thuc hien vdi m^t, hoac nhieu hang bdn dd ciia Atlat).
Tai liSu t h a m k h a o
1. Atiat Dia li Viet Nam, NXB Giao due, 2010.
2. Nguyen Dire Vu, Phdn tich bdng so li^u, ve bieu do, lucre do, dpc Atlat Dia li Vipt Nam, NXB Dgi hpc Qudc gia Hd Ndi, 2011.
S u m m m a r y Geographic Atlas of Vietnam is an important means of teaching, which is used
(Tiep trang 5) heavily on student leaming and test, test ... The process of using Vietnam Geographic Atlas often steps: setting up the outline (outline) knowledge extraction and exploitation of maps content; presented as written assignments. The exploitation of Atlas content under different owners have different specific outline.
TAP CHI THIFTBI GIAO DUC-SO 84-8/2012 • 3 9