第2章

【“guomubuwang(tiyanban)”yiqidong,chixushijian:59fen59miao。】

binglengerjingzhundedaojishisheng,rutongzhangubanzaiqinfengdenaohaizhongleixiang。

neiyishunjian,qinfengganjuezijidedanaofangfobeiyidaowuxingdedianliuchuanguo,zhenggeshijiezaitadeganzhizhongshunjianbiandebutong!

yanqiandekezhuo,muwendemeiyisixiweizouxiangdouqingxiderutongdaoke;kongqizhongpiaofudeweichen,zaitouguochuanglingdeyangguangxia,qiyundongguijidoufangfobeifangmanlewushubei,lilizaimu。tadeerduonengbuzhuodaojiaoshiwaizoulangshangqitabanjilaoshijiangkedemohushengyin,shenzhinengfenbianchugebibanhuaxuelaoshineidutedeshayasangyin。

gengrangtagandaozhenhandeshitadesiwei。

ruguoshuozhiqiandenaodaishiyitailaojiudebentengdiannao,yunxinggesaoleidoukadun,neimexianzai,tajiuxiangshishunjianshengjichenglezuidingjiandeliangzijisuanji!siweideyunzhuansudu、qingxidu、yijiduixinxidebuzhuohechulinengli,doudadaoleyigetayiwangxiangdoubuganxiangdekongbujingdi!

“zheijiushi……guomubuwang?”qinfengnannanziyu,yanzhongshanshuozhenanyizhixindeguangmang。

tameiyousihaoyouyu,jihushibennengdi,yibazhuaguozhuomianshangneibenzhanxinde、jihumeizenmefandongguode《gaozhongshuxuebixiuwu》,yijipangbianduijirushande《wuniangaokaoxnianmoni》、《huangxmijuan》、《xuebabiji》denggezhongfuxiziliao。

zheixiecengjingzaitayanzhongrutongtianshuyibandecunzai,cike,quesanfazheqiansuoweiyoudexiyinli。

“shijianzhiyouyixiaoshi!”qinfengshenxiyikouqi,qiangyaxiaxinzhongdejidang,muguangruiliruyingsun。

tashouxianjiangneidaoxitongfabude、haocheng“gaokaoyazhoutijibie(lveyouchaogang)”defuzahanshuti,shenshendiluoyinzainaohaizhong。meiyigefuhao,meiyigejiaobiao,meiyigetiaojian,douzai“guomubuwang”dejiachixia,beiwanmeifuke,fenhaobucha。

jinjiezhe,tafankaile《gaozhongshuxuebixiuwu》。

“唰唰唰——”

shuyefandongdeshengyinzaianjingdejiaoluolixiandegewaiqingxi。

qinfengdemuguangrutongzuijingmidesaomiaoyi,feisudilveguoshuyeshangdemeiyigezi、meiyigegongshi、meiyigeliti。

neixiecengjingrangtatoutongyulie、baisibudeqijiededingyi、dingli、tuilun,cikerutongwenshundemianyangban,guaiguaidiyongrutadenaohai,bingqiebeixunsuguilei、zhengli、jiyi。

“yuanlaihanshudedandiaoxingshizheimepanduande……”

“daoshudejiheyiyi……zhiqianzenmejiumeilijietoucheni?”

“zheigeluobidafaze,shushangjingranyoutidao!suiranzhishizaituozhanyueduli……”

wushucengjingmohubuqing、huozhegancuijiumeikanjinqudezhishidian,zai“guomubuwang”dekongbuxiaoguoxia,beitayiyizhongcuikulaxiubandesuduqiangxingjiyibingchubulijie。

tadedanaoxiangyikuaiganhedehaimian,fengkuangdixishouzhezhishideganlin。

duanduanshifenzhong,yibenhouhoude《bixiuwu》hexinneirong,jingranbeitahuluntunzaoban“ken”lexialai!suiranhenduoshencengcideluojiguanliantaweibinenglikeronghuiguantong,danzhishao,suoyoudegongshi、dinglihejibenjietibuzhou,tadoujideyiqingerchu!

这种感觉,太爽了!

jianzhijiuxiangshiwuxiaxiaoshuolidezhujiaobeidatonglerenduermai,xueshenmedoushiyidianjiutong!

qinfengshenzhinengqingxidiganjuedao,suizhezhishideyongru,taneiganggangtishengdao7diandezhili,zhengzaibeiyouxiaodiliyongqilai,bangzhutaduizheixieqiangxingjiyixialaidexinxijinxingchubudexiaohuaheshuli。

tameiyoutingxie,jinjiezheyouzhuaqile《wuniangaokaoxnianmoni》zhongguanyuhanshuyudaoshudebufen。

hailiangdetixing,gezhongdiaozuandekaofa,wuhuabamendejietijiqiao……

ruoshicongqian,guangshikandaozheixiemimimamadetimu,qinfengkongpajiuyijingtoupifama,zhijiexuanzefangqile。

danxianzai,taquekandejinjinyouwei,shenzhiyouxieruchiruzui。

meiyidaoti,zaitayanzhongdouxiangshiyigedengdaibeijiekaidemiti。tafeisudiyuedutimu,ranhouduizhaodaanjiexi,jianggezhongjietisilu、guanjianbuzhou、yicuodian,yiyimingjizaixin。

“yuanlaizheidaotikeyiyonggouzaohanshudefangfa……”

“zheigecanshufenlifa,yongzaizheilizhenshiqiaomiao!”

“haiyouzheizhonghuanyuanjiqiao,woyiqianzenmejiumeixiangdao?”

tadeetoushangshenchuleximidehanzhu,bushiyinweilei,ershiyinweidanaogaosuyunzhuandailaidexingfen。tadeyanshenzhuanzhuermingliang,fangfoyouliangtuanhuoyanzairanshao。

shijianyifenyimiaodiliushi。

sishifenzhonghou,qinfengjihujiangshoutousuoyouyuhanshu、daoshu、budengshi、jiexijihexiangguandehexinzhishidianhedianxingtixing,douyong“guomubuwang”denengliqiangxing“sai”jinlenaozili。

tadedanaocikejiuxiangyigebeisaimanledingjishicaidechaojibingxiang,suiranhenduodongxihaimeilaideji“pengrenxiaohua”,danzhishao,“yuancailiao”yijingchubeidaoleyigejingrendedibu!

【“guomubuwang(tiyanban)”shengyushijian:19fen37miao。】

xitongdetishiyinshishixiangqi。

“shijianbuduole,gaijiejueneidao‘lanluhu’le!”qinfengmuguangyining,jiangsuoyoukebenhexiticetuidaoyibian,shenxiyikouqi,zhongxinjiangzhuyilijujiaodaoneidaoxitongfabudeshuxuenantishang。

neishiyidaoyituoyuanweibeijing,jiehelehanshu、daoshu、budengshizhengmingyijicanshufanweitantaodechaojizonghedati。timutiaojianfanfu,shewencengcengdijin,jisuanlianghesiweiliangdoujiqikongbu。

ruoshisishifenzhongqian,qinfengkandaozheidaoti,kongpaliantimudoudubumingbai,gengbietijietile。

danxianzai,dangtazaicishenshizheidaotimushi,ganjuequejieranbutong。

neixiecengjingrutongluanmabandeshuxuefuhaohezhuanyeshuyu,cikezaitayanzhong,doubiandeqingximingle。tashenzhinengcongneirongzhangdetiganzhong,xunsubolichuhexindeyizhitiaojianhedaiqiuwenti。

“diyiwen,qiutuoyuancdebiaozhunfangcheng……zheigejiandan,liyonglixinlvhedianzaituoyuanshang,lianlifangchengzujike。”

qinfengdesiluyichangqingxi,naqibi,zaicaogaozhishangfeikuaidiyansuanqilai。

e=ca=22e=\frac{c}{a}=\frac{\sqrt{2}}{2}e=ac=22

x02a2+y0**2=1\frac{x_0^2}{a^2}+\frac{y_0^2}{b^2}=1a2x02+b2y02=1

a2=b2+c2a^2=b^2+c^2a2=b2+c2

jigejichugongshizaitanaohaizhongzidongfuxian,dairutimujichudejutishuzhi,yixilieyunsuanxingyunliushui。

“a²=2,b²=1。suoyituoyuancdefangchengwei:x22+y2=1\frac{x^2}{2}+y^2=12x2+y2=1。”

jinjinliangfenzhong,diyiwenbianbeitaqingsongnaxia。

“dierwen,shezhixianlyutuoyuancjiaoyua,bliangdian,ruodianp(1,1/2)manzupaxiangliang+pbxiangliang=0xiangliang,qiuzhixianldexielvk。”

“pa+pb=0,yiweizhepshiabdezhongdian。liyongdianchafahuozheweidadingli……”

qinfengdebijianzaicaogaozhishangfeiwu,gezhongjietifangfazaitanaohaizhongshanxian,bingbeixunsushaixuanchuzuiyoulujing。

shezhixianldefangchengweiy−12=k(x−1)y-\frac{1}{2}=k(x-1)y−21=k(x−1),dairutuoyuanfangcheng,xiaoquy,dedaoyigeguanyuxdeyiyuanercifangcheng。

(1+2k2)x2−(4k2−2k)x+(2k2−2k−32)=0(1+2k^2)x^2-(4k^2-2k)x+(2k^2-2k-\frac{3}{2})=0(1+2k2)x2−(4k2−2k)x+(2k2−2k−23)=0

liyongweidadinglixa+xb=4k2−2k1+2k2x_a+x_b=\frac{4k^2-2k}{1+2k^2}xa+xb=1+2k24k2−2k。

yinweipshiabzhongdian,suoyixp=xa+xb2=1x_p=\frac{x_a+x_b}{2}=1xp=2xa+xb=1。

4k2−2k2(1+2k2)=1\frac{4k^2-2k}{2(1+2k^2)}=12(1+2k2)4k2−2k=1

jiezheigeguanyukdefangcheng,dedaok=−1k=-1k=−1。

“dierwen,k=-1,yejiejuele!”qinfengdezuijiaobuzijuedigouqiyimoxiaorong。

zheizhonggongkenantide**,shitayiqiancongweitiyanguode!

zhenzhengdetiaozhan,shidisanwen。

“disanwen,zaidierwendetiaojianxia,guodianpzuozhixianmchuizhiyul,jiaotuoyuancyum,nliangdian。shiwenshifoucunzaiyigechangshuλ,shide|pm|·|pn|=λ|pa|·|pb|hengchengli?ruocunzai,qiuchuλdezhi;ruobucunzai,shuomingliyou。”

zheiyiwen,shejixianzhanggongshi、xiangliangmozhang、yijihengchengliwenti,jisuanlianghesiweinandudoudourantishenglehaojigedangci。

qinfengdemeitouweiweicuqi。

tanengganjuedao,zheiyiwendenandu,yijingchaochuletaganggangqiangxingjiyixialaideneixie“taolu”suonengzhijiejiejuedefanchou。taxuyaogengshencengcidelijiehegenglinghuodeyunyong。

“lengjing……zixifenxi……”qinfengbishangyanjing,naohaizhongganggang“tun”xiaqudewushuzhishidianrutongxingchenbanshanyao。

zhixianldexielvwei-1,zezhixianmdexielvwei1。

zhixianmdefangchengweiy−12=1(x−1)y-\frac{1}{2}=1(x-1)y−21=1(x−1),jiy=x−12y=x-\frac{1}{2}y=x−21。

jiangzhixianmdefangchengdairutuoyuanfangchengx22+y2=1\frac{x^2}{2}+y^2=12x2+y2=1,dedaoguanyuxdeyiyuanercifangcheng:

x22+(x−12)2=1\frac{x^2}{2}+(x-\frac{1}{2})^2=12x2+(x−21)2=1

x22+x2−x+14=1\frac{x^2}{2}+x^2-x+\frac{1}{4}=12x2+x2−x+41=1

32x2−x−34=0\frac{3}{2}x^2-x-\frac{3}{4}=023x2−x−43=0

6x2−4x−3=06x^2-4x-3=06x2−4x−3=0

shem(x₁,y₁),n(x₂,y₂),zex1+x2=46=23x_1+x_2=\frac{4}{6}=\frac{2}{3}x1+x2=64=32,x1x2=−36=−12x_1x_2=-\frac{3}{6}=-\frac{1}{2}x1x2=−63=−21。

∣pm∣⋅∣pn∣=(x1−xp)2+(y1−yp)2⋅(x2−xp)2+(y2−yp)2|pm|\cdot|pn|=\sqrt{(x_1-x_p)^2+(y_1-y_p)^2}\cdot\sqrt{(x_2-x_p)^2+(y_2-y_p)^2}∣pm∣⋅∣pn∣=(x1−xp)2+(y1−yp)2⋅(x2−xp)2+(y2−yp)2

youyudianm,nzaizhixiany=x−12y=x-\frac{1}{2}y=x−21shang,qiep(1,1/2)yezaizheitiaozhixianshang(yinweizhixianmguopdian),suoyipmhepndebiaodashikeyijianhua。

shijishang,pshixianmnshangdeyigedingdian。

∣pm∣⋅∣pn∣=∣(x1−xp)(x2−xp)∣⋅(1+km2)|pm|\cdot|pn|=|(x_1-x_p)(x_2-x_p)|\cdot(1+k_m^2)∣pm∣⋅∣pn∣=∣(x1−xp)(x2−xp)∣⋅(1+km2),zheilikm=1k_m=1km=1。

∣pm∣⋅∣pn∣=∣x1x2−xp(x1+x2)+xp2∣⋅(1+12)|pm|\cdot|pn|=|x_1x_2-x_p(x_1+x_2)+x_p^2|\cdot(1+1^2)∣pm∣⋅∣pn∣=∣x1x2−xp(x1+x2)+xp2∣⋅(1+12)

∣pm∣⋅∣pn∣=∣−12−1(23)+12∣⋅2=∣−12−23+1∣⋅2=∣−3+4−66∣⋅2=∣−16∣⋅2=13|pm|\cdot|pn|=|-\frac{1}{2}-1(\frac{2}{3})+1^2|\cdot2=|-\frac{1}{2}-\frac{2}{3}+1|\cdot2=|-\frac{3+4-6}{6}|\cdot2=|-\frac{1}{6}|\cdot2=\frac{1}{3}∣pm∣⋅∣pn∣=∣−21−1(32)+12∣⋅2=∣−21−32+1∣⋅2=∣−63+4−6∣⋅2=∣−61∣⋅2=31。

zheigejisuanguocheng,qinfengxiedejiweiliuchang。

jiexialaishijisuan|pa|·|pb|。

zhixianldefangchengweiy−12=−1(x−1)y-\frac{1}{2}=-1(x-1)y−21=−1(x−1),jiy=−x+32y=-x+\frac{3}{2}y=−x+23。

dairutuoyuanfangchengx22+y2=1\frac{x^2}{2}+y^2=12x2+y2=1:

x22+(−x+32)2=1\frac{x^2}{2}+(-x+\frac{3}{2})^2=12x2+(−x+23)2=1

x22+x2−3x+94=1\frac{x^2}{2}+x^2-3x+\frac{9}{4}=12x2+x2−3x+49=1

32x2−3x+54=0\frac{3}{2}x^2-3x+\frac{5}{4}=023x2−3x+45=0

6x2−12x+5=06x^2-12x+5=06x2−12x+5=0

shea(x₃,y₃),b(x₄,y₄),zex3+x4=126=2x_3+x_4=\frac{12}{6}=2x3+x4=612=2,x3x4=56x_3x_4=\frac{5}{6}x3x4=65。

tongyang,p(1,1/2)shixianabdezhongdian。

∣pa∣⋅∣pb∣=∣(x3−xp)(x4−xp)∣⋅(1+kl2)|pa|\cdot|pb|=|(x_3-x_p)(x_4-x_p)|\cdot(1+k_l^2)∣pa∣⋅∣pb∣=∣(x3−xp)(x4−xp)∣⋅(1+kl2),zheilikl=−1k_l=-1kl=−1。

youyupshiabzhongdian,suoyixp=x3+x42x_p=\frac{x_3+x_4}{2}xp=2x3+x4,zheiyiweizhex3−xp=−(x4−xp)x_3-x_p=-(x_4-x_p)x3−xp=−(x4−xp)。

yinci,∣pa∣⋅∣pb∣=∣pa∣2=(x3−xp)2(1+kl2)|pa|\cdot|pb|=|pa|^2=(x_3-x_p)^2(1+k_l^2)∣pa∣⋅∣pb∣=∣pa∣2=(x3−xp)2(1+kl2)。

x3,x4x_3,x_4x3,x4shifangcheng$6x^2-12x+5=0delianggegen。panbieshidelianggegen。panbieshidelianggegen。panbieshi\delta=(-12)^2-4\cdot6\cdot5=144-120=24>0。。。x_{3,4}=\frac{12\pm\sqrt{24}}{12}=1\pm\frac{2\sqrt{6}}{12}=1\pm\frac{\sqrt{6}}{6}。suoyi,。suoyi,。suoyi,x_3=1-\frac{\sqrt{6}}{6},,,x_4=1+\frac{\sqrt{6}}{6}(huoxiangfan,buyingxiangjieguo)。(huoxiangfan,buyingxiangjieguo)。(huoxiangfan,buyingxiangjieguo)。|x_3-x_p|=|1-\frac{\sqrt{6}}{6}-1|=\frac{\sqrt{6}}{6}。。。|pa|^2=(\frac{\sqrt{6}}{6})^2(1+(-1)^2)=\frac{6}{36}\cdot2=\frac{1}{6}\cdot2=\frac{1}{3}。suoyi,。suoyi,。suoyi,|pa|\cdot|pb|=\frac{1}{3}$。

“ng?|pm|·|pn|=1/3,|pa|·|pb|=1/3?”

qinfengkanzhecaogaozhishangdejieguo,yanzhongshanguoyisimingwu。

“ruguo|pm|·|pn|=λ|pa|·|pb|hengchengli,neimeλ=1?”

tazixijianchaleyibianzijidejisuanguocheng,meiyigebuzhoudouqingxiwuwu。

“guomubuwang”dailaidebujinjinshijiyili,haiyouyizhongduixijiedejizhidongchali,rangtahennanzaijisuanzhongchucuo。

ernei7diandezhili,suiranbugao,danzaicikeyefahuileguanjianzuoyong,rangtadeluojituilinenglishangleyigexiaotaijie。

【“guomubuwang(tiyanban)”shengyushijian:02fen15miao。】

时间所剩无几!

qinfengetouyijingbumanlehanzhu,dantayanshenqueyuelaiyueliang。

taxunsuzhenglisilu,jiangzhenggejietiguochengqingxi、wanzhengdishuxiezailingyizhangganjingdecaogaozhishang。zijisuiranyinweizhuiqiusuduerlvexianliaocao,danmeiyigebuzhoudoutiaoliqingxi,luojiyanjin。

dangtaxiexiazuihouyige“zongshangsuoshu,cunzaichangshuλ=1,shidedengshihengchengli”dejielunshi,naohaizhongdedaojishi,zhenghaotiaodaole“00fen03miao”。

“呼——”

qinfengzhangzhangdishuleyikouqi,zhenggerenrutongxutuoyiban,kaozaileyibeishang。

jihuzaitongshi,neizhongdanaorutongchaojijisuanjibangaosuyunzhuan、duiyiqiexinxiguomubuwangdeqiyiganjue,chaoshuibantuiqu。

tadedanaohuifulewangchangdezhuangtai,shenzhiyinweigangcaidechaofuheyunzhuan,haidaizheyisiqingweidepibeiheyunxuan。

dantaxinzhong,quechongmanleqiansuoweiyoudechongshiganhexiyue!

他做到了!

tajingranzhendedulijiejueleyidaoliantazijidoubuganxiangxiangdechaojinanti!

zheizhongtongguozishennuli(suiranyouxitongfuzhu)gongkenanguansuodailaidejudachengjiugan,shirenhedongxidouwufabinide!

xuexi,yuanlaiyekeyizheimeshuang!

jiuzaizheishi,binglengjixiedexitongtishiyin,ruyueerzhi:

【ding!xinshourenwu:dulizhengquejiedashuxuenanti,yiwancheng!】

【renwupingjia:youxiu(jietisiluqingxi,buzhouwanzheng,yongshi57fen57miao,fuheyuqi)。】

【zhengzaijiesuanrenwujiangli……】

qinfengdexinzangbuzhengqidijiasutiaodongqilai,yanzhongchongmanleqidai。

【gongxisuzhuhuodejiangli:10dianxueshenjifen!】

【gongxisuzhuhuodejiangli:“chujishuxuesiwei”(suipian1/3)!】

10点学神积分!

qinfengdeyanjingshunjianliangle!

zaizhiqiandexitongjieshaozhong,tayinyuejide,jifensihushixitongshangchenglideyingtonghuo,keyiyonglaiduihuangezhongshenqidedaojuhenengli!zheikeshishidashidehaodongxi!

ergengrangtajingxide,shineige“chujishuxuesiwei”suipian!

jiuzaixitongtishiyinluoxiadeshunjian,qinfengganjuedaoyiguweiruodanqueyichangxuanmiaodenuanliu,congzijimeixinchuyongrudanao。

jinjiezhe,tanaohaizhongguanyushuxuedeneixielingsande、tongguo“guomubuwang”qiangxingjiyixialaidezhishidian,fangfobeiyizhiwuxingdedashouqingqingbodongleyixia。

xuduozhiqianzhishijizhudanbingweiwanquanlijietouchedegongshidingli,cikejingranyouleyizhonghuorankailangdeganjue!

taduiganggangjiechudeneidaofuzahanshuti,yeyoulegengshenyicengdeganwu。

ruguorangtaxianzaizhongxinzuoyibian,tashenzhinengyinyueganjuedao,chulezijigangcaiyongdeneizhongjiefawai,sihuhaiyouqitagengjianjie、gengqiaomiaodesilu!

zheizhongganjuefeichangqimiao,jiuxiangshiyuanbenhundunyipiandeshuxueshijie,turanbeidianliangleyizhanxiaoxiaodemingdeng,suiranguangmangweiruo,quezuyizhaoliangyixiaopianquyu,rangtaduishuxuedeganzhihelijie,doutishengleyigeweixiaodecengci。

“zheijiushi‘chujishuxuesiwei’suipiandexiaoguoma?”qinfengxinzhongzhenhan。

jinjinshisanfenzhiyidesuipian,jiuyourucixiaoguo,neiruoshijiqilewanzhengde“chujishuxuesiwei”,shenzhishigenggaojideshuxuesiwei,neizijiqibushizhendenengchengweishuxuezhishen?

xitongdeshenqiheqiangda,zaiyicishuaxinletaderenzhi。

taditoukanlekanzijiyinweizhangshijianyongliwobieryouxiefahongdeshouzhi,youkanlekanneizhangxiemanletuiyanguochengdecaogaozhi。

suiran“guomubuwang”dexiaoguoyijingxiaoshi,dangangcaineiyigexiaoshidefengkuangxuexihejietiguocheng,queshenshendiluoyinzailetadejiyizhong。neixiebeita“tun”xiaqudezhishi,bingmeiyouwanquanxiaoshi,ershiyouyibufen,zaita7dianzhilihe“chujishuxuesiwei”suipiandeyingxiangxia,zhenzhengkaishichendianxialai,zhuanhuaweitazijidedongxi。

“xueshenheikejixitong……”qinfengdeyanzhongshanshuozheqiansuoweiyoudeguangmang。

juewangzaoyibeiyisaoerkong,querdaizhide,shixiongxiongranshaodexiwanghedouzhi!

tazhidao,congjihuozheigexitongkaishi,taderensheng,yijingchedibuyiyangle!

xuezhadenixizhilu,caiganggangkaishi!

ertashouzhongzhei10dianbaoguidexueshenjifen,yijineishenmide“chujishuxuesiwei”suipian,jiushitatashangzheitiaonixizhiludediyitongjin!

jiexialai,gaihaohaoyanjiuyixia,zhei10dianjifen,nengjizijidailaishenmeyangdejingxile!

qinfengdezuijiao,buyouzizhudiyangqiyimochongmanqidaidexiaorong。