福建省部分地市2023届高中毕业班适应性练习数学答案
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福建省2023届高中毕业班适应性练习卷数学参考答案及评分细则评分说明:1.本解答给出了一种或几种解法供参考,如果考生的解法与本解答不同,可根据试题的主要考查内容比照评分标准制定相应的评分细则。2.对计算题,当考生的解答在某一步出现错误时,如果后继部分的解答未改变该题的内容和难度,可视影响的程度决定后继部分的给分,但不得超过该部分正确解答应给分数的一半;如果后继部分的解答有较严重的错误,就不再给分。3.解答右端所注分数,表示考生正确做到这一步应得的累加分数。4.只给整数分数。选择题和填空题不给中间分。一、选择题:本大题考查基础知识和基本运算。每小题5分,满分40分。1.D2.B3.C4.A5.D6.D7.A8.B二、选择题:本大题考查基础知识和基本运算。每小题5分,满分20分。全部选对的得5分,部分选对的得2分,有选错的得0分。9.BC10.ABD11.ACD12.BD三、填空题:本大题考查基础知识和基本运算。每小题5分,满分20分。13.yx=−2,yx=−+2(只需填其中的一个即可)122114.215.,216.3a,aa,2323四、解答题:本大题共6小题,共70分。解答应写出文字说明、证明过程或演算步骤。17.本小题主要考查正弦定理、余弦定理、三角恒等变换、三角形面积及平面向量等基础知识,考查直观想象能力、逻辑推理能力、运算求解能力等,考查化归与转化思想、函数与方程思想、数形结合思想等,考查数学运算、逻辑推理、直观想象等核心素养,体现基础性和综合性.满分10分.π解法一:(1)因为b=+2sincA,在△ABC中,由正弦定理得,6sin2sinBC=+Asin,.................................................................................................................1分6又因为sinsinBAC=sin−−AC(=+)(),所以sin(AC+)=2sinsinCA+,...............................................................................................2分631展开得sincosACACcossinC+A=A+2sinsincos,........................................................3分22即sincosACCA3sin−=sin0,3因为sinA0,故cos3sinCC=,即tanC=.........................................................................4分3又因为C(0,),所以C=...........................................................................................................5分6(2)设△ABC的外接圆的圆心为O,半径为R,数学参考答案及评分细则第1页(共20页)
2因为BABD=BA,所以BABD−(=BA)0,即BAAD=0,所以DABA⊥.......................................................................................................................................6分故BD是O的直径,所以BCCD⊥.c1在△ABC中,c=1,22R===,所以BD=2....................................................7分sinBCAsin622在△ABD中,AD=BD−AB=3.22设四边形ABCD的面积为S,BCx=,CDy=,则xy+=4,..............................................8分1131SS=S+ABAD=+=+BCCDxy.....................................................................9分△ABDCBD△222222313xy++=+1,2222当且仅当xy==2时,等号成立.3所以四边形ABCD面积最大值为+1.........................................................................................10分2解法二:(1)同解法一;...................................................................................................................5分(2)设△ABC的外接圆的圆心为O,半径为R,BD在BA上的投影向量为BA,222所以BABD==BABABA().又BABD=BA=BA,所以=1,所以BD在BA上的投影向量为BA.所以DABA⊥.......................................................................................................................................6分故BD是O的直径,所以BC⊥CD.c1在△ABC中,c=1,22R===,所以BD=2....................................................7分sinBCAsin622在△ABD中,ADBD=−AB=3.π设四边形ABCD的面积为S,=CBD,0,,2则CB=2cos,CD=2sin,.........................................................................................................8分113S=+S=SABAD+=+CBCDsin2...................................................................9分△ABDCBD△222π3当2=时,S最大,所以四边形ABCD面积最大值为+1.................................................10分22解法三:(1)同解法一;...................................................................................................................5分数学参考答案及评分细则第2页(共20页)
(2)设△ABC的外接圆的圆心为O,半径为R,2因为BABD=BA,所以BABD−(=BA)0,即BAAD=0,所以DABA⊥.......................................................................................................................................6分故BD是O的直径,所以BCCD⊥.c1在△ABC中,c=1,22R===,所以BD=2....................................................7分sinBCAsin622在△ABD中,AD=BD−AB=3.设四边形ABCD的面积为S,点C到BD的距离为h,113则SS=S+ABAD=+=BDh+h.........................................................................9分△ABDCBD△2223当hR==1时,S最大,所以四边形ABCD面积最大值为+1..............................................10分2解法四:(1)同解法一;...................................................................................................................5分(2)设△ABC的外接圆的圆心为O,半径为R,c1在△ABC中,c=1,22R===,.........................................................................6分sinBCAsin6故△ABC外接圆O的半径R=1.π即OAOB===AB1,所以=AOB.3如图,以△ABC外接圆的圆心为原点,OB所在直线为x轴,13建立平面直角坐标系xOy,则A,,B(1,0).22因为C,D为单位圆上的点,设C(cos,sin),D(cos,sin),其中(0,2π),(0,2).13所以BABD=−=−,cos1,sin,(),...................................................................................7分222113代入BABD=BA,即BABD=1,可得−++cos=sin1,.......................................8分2221即sin−=.62ππ11ππππ5ππ由(0,2)可知−−,,所以解得−=或−=,即=或=π.66666663数学参考答案及评分细则第3页(共20页)
π当=时,A,D重合,舍去;当=π时,BD是O的直径.3设四边形ABCD的面积为S,1313则S=S+S=BD+BDsin=+sin,.......................................................9分△ABD△CBD22223π由(0,2π)知sin1,所以当=时,即C的坐标为(0,1−)时,S最大,23所以四边形ABCD面积最大值为+1.........................................................................................10分218.本小题主要考查指数与对数基本运算、递推数列、等差数列、等比数列及数列求和等基础知识,考查运算求解能力、逻辑推理能力和创新能力等,考查化归与转化思想、分类与整合思想、函数与方程思想、特殊与一般思想等,考查逻辑推理、数学运算等核心素养,体现基础性、综合性和创新性.满分12分.解法一:(1)由aaa+=log,得a=2aa21nn2−+1+,.............................................................2分21n2n−+1n222n则a=2aa21nn2++3+,从而aa=2=2a2a12na2n−a1n+2an++1na+2+n−a3n++2+1+21232,.........................................3分22n+22nn2+又aa==162aa21nn2++14,..............................................................................................................4分22nn2+所以aaaa++24=,......................................................................................................5分21n2n−1n+2+3n+21即aaa+=2,所以a是等差数列.............................................................................6分21n2+3n−+n2121n−(2)设等差数列a的公差为d.21n−当n=1时,aa+=alog,即1log8+=a,132232所以a=2,所以da=a−=1,.....................................................................................................7分331所以数列a是首项为1,公差为1的等差数列,21n−所以an=;.......................................................................................................................................8分21n−又a==2=2aa212nn2−+1+nn++(1)21n+;.......................................................................................................9分2nS9=a1+a2+a3+a4+a5+a6+a7+a8+a9=(a1+a3+a5+a7+a9)+(a2+a4+a6+a8)3579=(12345++++)+(2+2+2+2)=15680+=6952023,11又SSa=+=+=695227432023;10910数学参考答案及评分细则第4页(共20页)
又a0,则SS,且SS2023,..................................................................................11分nnn+1910所以n的最小值为10.........................................................................................................................12分解法二:(1)由a0,且aa=16a21n+,2n2nn2+2则loglog16(aa)=a21n+,............................................................................................................2分22222nn+得loglogaa4a+=,..........................................................................................................4分22222n2n1n++因为aaa+=log,aaa+=log,21n2n−+1n2221n2n+3n+2+22所以(a+++a)(aa)=4a,........................................................................................5分2n−12n+12n+12n+32n+1即a+=a2a,所以a是等差数列...............................................................................6分2n−+12n32+1n21n−(2)设等差数列a的公差为d.21n−当n=1时,a+=aloga,即1log8+=a,132232所以a=2,所以da=a−=1,.....................................................................................................7分331所以数列a是首项为1,公差为1的等差数列,21n−所以an=;....................................................................................................................................8分21n−又a2a1na2n−+1n22+=log,所以a=2aa2nn−+1+21=2nn++(1)=221n+;................................................................................................9分2n当kN时,Saa=aa++++21kk232=+(+a1+a35a+2a+a+12a+46a+2a+kk−)()35721k+=(123+++22+k)2+2+(+++)kkk(+1)84(1−)=+,23++1184k−124−k8kk(kk)()21k+()SS=a−=+−=+2,2kk−1k222323数学参考答案及评分细则第5页(共20页)
556−248所以SS==+=6952023,9251−2355684(1−)SS==+=27432023,102523又a0,则SS,且SS2023,..................................................................................11分nnn+1910所以n的最小值为10.........................................................................................................................12分解法三:(1)同解法一;...................................................................................................................6分(2)设等差数列a的公差为d.21n−当n=1时,aa+=alog,即1log8+=a,132232所以a=2,所以da=a−=1,.....................................................................................................7分331所以数列a是首项为1,公差为1的等差数列,21n−所以an=;....................................................................................................................................8分21n−又a=2aa2nn−+1+21=2nn++(1)=221n+;....................................................................................................9分2n当kN时,Saaaa=++++21kk1−−2321=+(+a1+a35a+2a+a+12a+46a+2a+2kk−−)()35721k−=+++(123+2+2+2+2++k)()kk(kk++11)14−k−1()84(1k−1−)=+=+8,21423−45684(1−)251+所以SS==+=6952023,SSa=++==695227432023.9251−1091023又a0,则SS,且SS2023,..................................................................................11分nnn+1910所以n的最小值为10.........................................................................................................................12分19.本小题主要考查一元线性回归模型、条件概率与全概率公式等基础知识,考查数学建模能力、运算求解能力、逻辑推理能力、直观想象能力等,考查统计与概率思想、分类与整合思想等,考查数学抽象、数学建模和数学运算等核心素养,体现应用性和创新性.满分12分.解:(1)由散点图判断yc=ln(x−+2012)d适宜作为该机场飞往A地航班放行准点率y关于年份数x数学参考答案及评分细则第6页(共20页)
的经验回归方程类型...........................................................................................................................1分令tx=−ln(2012),先建立y关于t的线性回归方程.10tyiity−101226.8101.580.4−ˆi=14由于c===,........................................................................2分1022227.7101.5−tti−10i=1dˆyct=−=−ˆ=80.441.574.4,.......................................................................................................3分该机场飞往A地航班放行准点率y关于t的线性回归方程为yˆ=4t+7.44,因此y关于年份数x的回归方程为yˆ=4ln(2012)7x−+4.4............................................................4分所以当x=2023时,该机场飞往A地航班放行准点率y的预报值为yˆ=4ln(20232012)74.4−+=4ln1174.4+42.4074.484+=.所以2023年该机场飞往A地航班放行准点率y的预报值为84%.................................................5分(2)设A=“该航班飞往A地”,A=“该航班飞往B地”,A=“该航班飞往其他地区”,123C=“该航班准点放行”,.....................................................................................................................6分则PA()=0.2,PA()=0.2,PA()=0.6,123PCA(1)=0.84,PCA(2)=0.8,PCA(3)=0.75..........................................................................7分(i)由全概率公式得,PC(PAPCA)=++(11)2233(PAPCA)()PAPCA()()()................................................................8分=0.840.20.80.20.750.6++=0.778,所以该航班准点放行的概率为0.778................................................................................................9分PAC(1)PAPCA(11)()0.20.84(ii)PAC()===,1PC()PC()0.778PAC(2)PAPCA(22)()0.20.8PAC()===,2PC(PC)()0.778PAC(3)PAPCA(33)()0.60.75PAC()===,..............................................................11分3PC()PC()0.778因为0.60.750.20.840.20.8,所以可判断该航班飞往其他地区的可能性最大......................................................................12分20.本小题主要考查直线与直线、直线与平面、平面与平面的位置关系,空间几何体的体积、平面与平面的夹角等基础知识;考查直观想象能力,逻辑推理能力,运算求解能力等;考查化归与转化思想,数数学参考答案及评分细则第7页(共20页)
形结合思想,函数与方程思想等;考查直观想象,逻辑推理,数学运算等核心素养;体现基础性和综合性.满分12分.解法一:(1)如图1,取AB中点O,连接PO,CO.因为PAPB==2,AB=2,所以POAB⊥,PO=1,BO=1.又因为ABCD是菱形,=ABC60,所以CO⊥AB,CO=3.222因为PC=2,所以PC=+POCO,所以PO⊥CO.又因为AB平面ABCD,CO平面ABCD,ABCOO=,所以PO⊥平面ABCD........................................................................................................................2分因为ADBC∥,BC平面PBC,AD平面PBC,1133所以AD∥PBC平面,所以V=V=V=POS=14=................3分DPBC−−−APBCPABC△ABC334331因为VV==,.............................................................................................................4分MPBC−−DPBC621所以点M到平面PBC的距离是点D到平面PBC的距离的,2所以PMMD=.....................................................................................................................................5分(图1)(图2)(2)由(1)知,BO⊥CO,PO⊥BO,PO⊥CO,如图2,以O为坐标原点,OC,OB,OP的方向分别为x轴,y轴,z轴正方向建立空间直角坐标系,.......................................................................................................................................................6分31则A(0,1,0−),B(0,1,0),C(3,0,0),D(3,2,0−),P(0,0,1),所以M,1,−.2231则AC=(3,1,0),BC=−(3,1,0),BD=−(3,3,0),AP=(0,1,1),CM=−,1,−.22因为QAP,设AQAP==(0,,),则CQAQ=−AC=−−(3,1,),数学参考答案及评分细则第8页(共20页)
因为BD∥,Q,C,M,故存在实数ab,,使得CQaCM=+bBD,...............7分43a=,−ab+3=−3,321所以−−ab3=−1,解得b=−,3a=,22=.312所以CQ=−−3,,.......................................................................................................................8分33yz2n=CQ0,−3x−+=0,1设平面BCQ的法向量为n1=(,,)xyz,则即33n1=BC0,30xy−=.取x=1,得到平面BCQ的一个法向量n=(1,3,23).............................................................10分1设平面BCQ与平面ABCD夹角是,又因为n=(0,0,1)是平面ABCD的一个法向量,.........................................................................11分2nn123则coscos=,==nn.12nn2123所以平面BCQ与平面ABCD夹角的余弦值是......................................................................12分2解法二:(1)如图3,取AB中点O,连接PO,CO,因为PAPB==2,AB=2,所以POAB⊥,PO=1,BO=1,又因为ABCD是菱形,=ABC60,(图3)所以COAB⊥,CO=3.222因为PC=2,所以PCPO=+CO,所以POCO⊥.因为AB平面PAB,PO平面PAB,ABPOO=,所以CO⊥平面PAB...........................................................................................................................2分1113V=V=COS=322=................................................................3分APBC−−CABP△ABP3323过M作MN∥AD交AP于点N,ADBC∥,所以MN∥BC,又BC平面PBC,MN平面PBC,数学参考答案及评分细则第9页(共20页)
13所以MN∥PBC平面,所以VVVCOS====,MPBC−−−NPBCCNBPNBP△3611因为VCOS=,VCOS=CABP−ABP△CNBP−NBP△33所以SS=2,..........................................................................................................................4分△ABPNBP△所以N是PA的中点,所以M是PD的中点,所以PMMD=......................................................5分(2)在平面ABCD内,过C作EFBD∥交AD延长线于点E,交AB延长线于点F,因为ABCD是菱形,所以ADDE=.如图4,在平面PAD内,作PPAE∥交EM的延长线于点P,设EP交AP于点Q.所以,四边形EDPP是平行四边形,PPDEPP=,DE∥,PQPP1所以△QPPQAE∽△,所以==,AQAE2所以点Q是线段PA上靠近P的三等分点.........................................................................................7分如图5,在平面PAB内,作QT∥PO,交AB于T,因为PO⊥平面ABCD,所以QT⊥平面ABCD,所以QT⊥BC,22因为PO=1,QTPO==,.........................................................................................................8分33在平面ABCD内,作TNBC⊥,交BC于点N,连接QN,过A作AK∥TN交BC于K,3在△ABK中,AB=2,=ABK60,所以AKAB==3,2(图5)22所以TN==AK3,....................................................................................................................9分33因为QT⊥BC,TNBC⊥,QTTNT=,所以BC⊥平面QTN,因为QN平面QTN,所以BCQN⊥.所以QNT是二面角ABCQ−−的平面角..................................................................................11分数学参考答案及评分细则第10页(共20页)
QT33在Rt△QTN中,tanQNT==,所以cos=QNT.NT323所以平面BCQ与平面ABCD夹角的余弦值是......................................................................12分2解法三:(1)同解法一;.................................................................................................................................5分(2)由(1)知,BOCO⊥,POBO⊥,POCO⊥,如图2,以O为坐标原点,OC,OB,OP的方向分别为x轴,y轴,z轴正方向建立空间直角坐标系,.......................................................................................................................................................6分31则A(0,1,0)−,B(0,1,0),C(3,0,0),D(3,2,0)−,P(0,0,1),所以M(,1,)−.2231则AC=(3,1,0),BC=−(3,1,0),BD=−(3,3,0),AP=(0,1,1),CM=−(,1,)−.2233xy0,−=n=BD0,设平面的法向量为n=(,,)xyz,则即31n=CM0,−−+=xyz0.22取y=1,得到平面的一个法向量n=(3,1,5)..........................................................................7分因为QAP,设AQ==AP(0,,),则CQAQ=−AC=−−(3,1,),212因为n=−+CQ−+315=0,所以=,所以CQ=−3,−,.......................................8分333yz112n=CQ0,−−+3=0,x11设平面BCQ的法向量为n111=1(,,)xyz,则即33n1=BC0,30xy−=.11取x=1,得到平面BCQ的一个法向量n=(1,3,23)............................................................10分11设平面BCQ与平面ABCD夹角是,又因为n=(0,0,1)是平面ABCD的一个法向量,.........................................................................11分2nn123则cos=cosnn,==.12nn2123所以平面BCQ与平面ABCD夹角的余弦值是......................................................................12分221.本小题主要考查圆、椭圆的标准方程及简单几何性质,直线与椭圆的位置关系等基础知识;考查运算数学参考答案及评分细则第11页(共20页)
求解能力,逻辑推理能力,直观想象能力和创新能力等;考查数形结合思想,函数与方程思想,化归与转化思想等;考查直观想象,逻辑推理,数学运算等核心素养;体现基础性,综合性与创新性.满分12分.解法一:(1)由题意得,A(−1,0),A(1,0).12因为D为BC中点,所以AD1BC⊥,即AD12AC⊥,...................................................................1分又PEAD∥1,所以PE⊥AC2,又E为AC2的中点,所以PA2PC=,所以PA1+PA2=PA1+PC=AC1=4AA12,所以点P的轨迹是以AA12,为焦点的椭圆(左、右顶点除外)................................................2分22xy222设:+=1(xa),其中ab0,abc−=.22ab22则24a=,a=2,c=1,ba=c−=3..............................................................................3分22xy故:+=1(x2)..........................................................................................................4分43(2)结论③正确.下证:△QCC12的面积是定值.......................................................................5分由题意得,B1(−2,0),B2(2,0),C1(0,1−),C2(0,1),且直线l2的斜率不为0,可设直线l:xmy=−1,Mxy(,,,Nxy)(),且x2,x2.2112212xy22+=1,22由43得(3m46y9my+0−−=),.................................................................................6分xmy=−1,69m−所以y1y2yy+12==22,,............................................................................................7分3mm434++所以23myy12y1y2=−+().y1y2直线BM1的方程为:yx=+(2),直线BN2的方程为:yx=−(2),....................8分x1+2x2−2y1yx=+(2,)x1+2由yx=−y2(2,)x−22数学参考答案及评分细则第12页(共20页)
x+2yx21(+2)得=............................................................................................................................9分xyx−−2212()331ymy(+1)myyy+−++(y1y2y2)−−yy121=21=122=2=22=,ymy12(−3)myy12y1−3−+3−(yyy)3−−93yy312112222解得x=−4......................................................................................................................................11分故点Q在直线x=−4,所以Q到CC12的距离d=4,11因此△QCC12的面积是定值,为CC12d==244.........................................................12分22解法二:(1)同解法一....................................................................................................................4分(2)结论③正确.下证:△QCC12的面积是定值.......................................................................5分由题意得,B1(−2,0),B2(2,0),C1(0,1−),C2(0,1),且直线l2的斜率不为0,可设直线l:xmy=−1,Mxy(,,,Nxy)(),且x2,x2.2112212xy22+=1,22由43得(3m46y9my+0−−=),.................................................................................6分xmy=−1,69m−所以y1+y2=22,yy12=,............................................................................................7分3mm++434所以23myy12y1y2=−+().y1y2直线BM1的方程为:yx=+(2),直线BN2的方程为:yx=−(2),....................8分x1+2x2−2y1yx=+(2,)x1+2由yx=−y2(2,)x2−2yx21yx(12++22−)()得x=2........................................................................................................9分yx21yx(12+−22−)()ymy21(12ymy++13−)()23myy12y2y+−1=2=2ymy21(12ymy+−13−)()yy21+3数学参考答案及评分细则第13页(共20页)
23myy2312y1y+2y2+y1−(+)()==−24............................................................................11分yy21+3故点Q在直线x=−4,所以Q到CC12的距离d=4,11因此△QCC12的面积是定值,为CC12d==244.........................................................12分22解法三:(1)同解法一....................................................................................................................4分(2)结论③正确.下证:△QCC12的面积是定值.......................................................................5分由题意得,B1(−2,0),B2(2,0),C1(0,1−),C2(0,1),直线l2的斜率不为0.22xyx=−1,x=−1,+=1,(i)当直线l2垂直于x轴时,l2:x=−1,由43得3或3=−y=−y=.x12233不妨设MN−1,−−,1,,2231则直线BM1的方程为:yx=+(2),直线BN2的方程为:yx=−(2),223yx=+(2,)x=−4,2由得所以Q(4,3)−−,yx=−1(2)y=−3,211故Q到CC12的距离d=4,此时△QCC12的面积是CC12d==244.............................6分22(ii)当直线l不垂直于x轴时,设直线l:ykx=+(1),Mxy(,,,Nxy)(),且x2,x2.211221222xy+=1,2222由43得(43kx8kx4+12++k)0−=(),.................................................................7分ykx=+(1,)22−−8kk412所以x1x2xx+12==22,.............................................................................................8分43kk43++y1y2直线MB1的方程为:yx=+(2),直线MB2的方程为:yx=−(2),.....................9分x1+2x2−2y1yx=+(2,)x1+2由yx=−y2(2,)x−22数学参考答案及评分细则第14页(共20页)
yx21yx(12++22−)()得x=2......................................................................................................10分yx21yx(12+−22−)()kx(2+1)(x1+2)+kx(1+1)(x2−2)42xx126x1x−+2=2=.kx(2+1)(x1+2)−kx(1+1)(x2−2)34xx12++4xx12−+2x16x2下证:=−4.34xx12++即证42xx12643x1x−2x1+42x=−++(),即证410xx1216x1x2=−+−(),412kk228−−即证41016=−−,2243kk43++222即证44(12kkk10−=−8164)−−+3()(),上式显然成立,.................................................................................................................................11分故点Q在直线x=−4,所以Q到CC12的距离d=4,11此时△QCC12的面积是定值,为CC12d==244.22由(i)(ii)可知,△QCC12的面积为定值..................................................................................12分解法四:(1)同解法一....................................................................................................................4分(2)结论③正确.下证:△QCC12的面积是定值.......................................................................5分由题意得,B1(−2,0),B2(2,0),C1(0,1−),C2(0,1),且直线l2的斜率不为0,可设直线l:xmy=−1,Mxy(,,,Nxy)(),且x2,x2.2112212xy22+=1,22由43得(3m46y9my+0−−=),.................................................................................6分xmy=−1,69m−所以y1y2yy+12==22,.............................................................................................7分3mm434++y1y2直线BM1的方程为:yx=+(2),直线BN2的方程为:yx=−(2),....................8分x1+2x2−2数学参考答案及评分细则第15页(共20页)
22xy22y23x2+2因为+=1,所以=−,43x2−24y23x2+2故直线BN2的方程为:yx=−−(2).4y2y1yx=+(2,)x1+2由3x2+2yx=−−(2,)4y2x−24yy12得=−...............................................................................................................9分xx+x+2+322(12)()4yy4yy49−=−12=−12=−=3,31(mx1my++)()3myy2my+++y()13−9+6m+3+m2422m121212()解得x=−4......................................................................................................................................11分故点Q在直线x=−4,所以Q到CC12的距离d=4,11因此△QCC12的面积是定值,为CC12d==244.........................................................12分2222.本小题主要考查导数及其应用、函数的单调性、不等式等基础知识,考查逻辑推理能力、直观想象能力、运算求解能力和创新能力等,考查函数与方程思想、化归与转化思想、分类与整合思想等,考查逻辑推理、直观想象、数学运算等核心素养,体现基础性、综合性和创新性.满分12分.x解法一:(1)fxx(a)=++(1e),.................................................................................................1分故xa−−1时,fx()0;xa−−1时,fx()0....................................................................2分当−−a10,即a−1时,fx()在(0,1−−a)单调递减,在(−−+a1,)单调递增;当−−a10,即a≥−1时,fx()在(0,+)单调递增.综上,当a−1时,fx()在(0,1−−a)单调递减,在(−−+a1,)单调递增;当a≥−1时,fx()在(0,+)单调递增.............................................................................................4分(2)不存在axx,,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.............5分010101证明如下:假设存在满足条件的axx,,,01因为fx()在(xfx,())处的切线方程为yfx−=−f(xxx)()()00000数学参考答案及评分细则第16页(共20页)
xx002即yx=a++x(axax+−1e)−e(),.......................................................................................6分000xx112同理fx()在(xfx,())处的切线方程为yx=a++x(axax+1e−)−e(),11111(xax++a=1e++)1e,x0()x101且它们重合,所以...................................................................7分(ax−ax−=a22−xax−)ee,x0()x1001122整理得(xaa++xaxx−11a−)a(=x++ax−−)()(),01110022即xx+(a+1)(x+x)+a+2a=0,xx+(a+1)(x+x)+(a+1)=1,01010101所以(x++a1)(x++a1)=1,..........................................................................................................8分01由(1)exax++(a1)e=++x0x1两边同乘以ea+1,01得(1)exax++(a1)e=++xa0++1xa1++1,..............................................................................................9分01ttee,t0=t101令tx00a=++1,t11xa=++1,则且tt01,tt=1,011由tt=1得t=1,代入tteet0=t1得eett11=t2,两边取对数得1=+2lntt...........................10分01001111tt111令gt()tt2ln=+−,t2121(t+1)当t0时,gt()tt2ln=+−,gt()1=0++=≥,22tttt所以gt()在(0,+)上单调递增,又g(10)=,所以t=1,从而t=1,与tt矛盾;.........11分10012121(t+1)当t0时,gt()tt2ln=−+−(),gt()1=0++=≥,22tttt所以gt()在(,0)−上单调递增,又g(−=10),所以t=−1,从而t=−1,与tt矛盾;1001ttee,t0=t101综上,不存在tt01,,使得且tt01.tt=1,01故不存在axx,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.....................12分010101解法二:(1)同解法一;....................................................................................................................4分数学参考答案及评分细则第17页(共20页)
(2)不存在axx,,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.............5分010101证明如下:假设存在满足条件的axx,,,01因为fx()在(xfx,())处的切线方程为yfx−=−f(xxx)()()即00000y=(x++a1e)x0+x(x+a)ex0−xx(++a1e)x0,......................................................................6分0000同理fx()在(xfx,())处的切线方程为yx=a++x(xaxx+a+1e)−++ex1x11ex1()(),111111(xax++a=1e++)1e,x0()x101且它们重合,所以..........................7分(xaxx+−++)ae1exxx00a=xxe+1e,−(++a)()xx11()000111整理得(xax++axx+−1a)(1)xa1x++(a1)xx=a+++−++(),01111000令txa=++1,t=x++a1,可得tt=1....................................................................................8分001101由(1)exax++(a1)e=++x0x1两边同乘以ea+1,01ttee,t0=t1得(1)exax++(a1)e=++xa0++1xa1++1,则01且tt,....................................................9分0101tt=1,01令()ethtt=,则ht(01)=ht(),且tt01.由(1)知,当t−1时,ht()单调递增,当t−1时,ht()单调递减,又当t0时,ht()0,当t0时,ht()0,所以若tt,存在,不妨设tt−10,011011设2t=−,t10mt=,m1,又tt01=1,所以t0=,则0mm由tteet1=t0,得mteemt00=tt即meemt00t=,1000lnm则lnmmt+=t,所以t=,0001−m1lnm1所以−=,即lnmm+−=0,................................................................................11分m1−mm2121(1)x−令gx()x2lnx=−+,x≥1,则gx()1=0−−=−,22xxxx所以gx()在(1,)+上单调递减,所以当x1时,gx()g(1)=0,数学参考答案及评分细则第18页(共20页)
11即2lnxx−,取xm=,即ln0mm+−,xm1所以ln0mm+−=在m1时无解,mttee,t0=t101综上,不存在tt01,,使得且tt01.tt=1,01故不存在axx,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.....................12分010101解法三:(1)同解法一;....................................................................................................................4分(2)不存在axx,,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.............5分010101证明如下:假设存在满足条件的axx,,,01因为fx()在(xfx,())处的切线方程为yfx−=−f(xxx)()()00000xx002即yx=a++x(axax+−1e)−e(),.......................................................................................6分000xx112同理fx()在(xfx,())处的切线方程为yx=a++x(axax+1e−)−e(),11111(xax++a=1e++)1e,x0()x101且它们重合,所以...................................................................7分(ax−ax−=a22−xax−)ee,x0()x1001122整理得(x++a11)(a−x−ax)=(x++a)(a−x−ax),01110022即xxa+xx+(a+a++1=)2(0),xx+(a+1)(x+x)+(a+1)=1,01010101所以(xax++a++1)1(1=),..........................................................................................................8分01由(x++a1)ex0=(x++a1)ex1两边同乘以ea+1,01得(1)exax++(a1)e=++xa0++1xa1++1,..............................................................................................9分01ttet0=e,t101令tx00a=++1,t11=x++a1,则且tt01,tt=1,01令()etht=t,则ht(ht01)=(),且tt01.由(1)知,当t−1时,ht()单调递增,当t−1时,ht()单调递减,又当t0时,ht()0,当t0时,ht()0,数学参考答案及评分细则第19页(共20页)
所以若tt,存在,不妨设tt−10,0110则tt−tt=−ee01,lnln(−t+t0t=0)t1−1+(),01(−tt−−01)()所以=1....................................................................................................................11分lnln(−tt−01−)()(−tt−−01)()以下证明−−(tt01)().lnln(−tt−01−)()2121(1)x−令gx()x2lnx=−+,x≥1,则gx()1=0−−=−,22xxxx所以gx()在(1,+)上单调递减,所以当x1时,gx()=g(1)0,因为−t1,所以−t1,−−tt11−t0,1g0ln0−+−t−t−t−t−t00001(−tt−−01)()整理得−−(tt01)().lnln(−tt−01−)()(−tt−−01)()因为=1,所以(−tt−)()1,与tt=1矛盾;0101lnln(−tt−01−)()ttee,t0=t101所以不存在tt01,,使得且tt01.tt=1,01故不存在axx,,且xx,使得曲线yfx=()在xx=和xx=处有相同的切线.....................12分010101数学参考答案及评分细则第20页(共20页)
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