数学参考答案
一、单选题:本题共8小题,每小题5分,共40分. 在每小题给出的四个选项中,只有一项是符合题目要求的. 1.C 2.D 3.A 4.B 5.C(教材P140.3) 6.B 7.A B10) (教材P222.例6) 8.(教材P58.
二、多选题:本题共4小题,每小题5分,共20分. 在每小题给出的四个选项中,有多个选项符合题目要求,全部选对的得5分,选对但不全的得3分,有选错的得0分. 9.ABD 10.CD 11.BC 12.BC
三、填空题:本题共4小题,每小题5分,共20分. 13.2 14.π 15.32;22(教师用书P52.12) 16. (教材P231问题、教材P245例2) 解析:以枢轮中心为原点建立坐标系,则
16.13
P点纵坐标:y1=1.7sinπππ+x=1.7cosx; 水面纵坐标:y2=−1.19−0.017x,21515P点进入水中,则1.7cosx−1.19−0.017x,即cosx−0.7−0.01x,
1515y=cos作出x和y=−0.7−0.01x的图象,在10,1515存在一个交点,令h(x)=cosx+0.7+0.01x, 15因为h(12)0,h(13)0,所以点P至少经过13分钟进入水中.
四、解答题:本题共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.本题考查函数的基本性质、二次不等式、韦达定理等基础知识;考查推理论证、运算求解等能力;考查函数与方程、化归与转化、数形结合等思想.满分10分.
···················································· 1分 解:由g(x)=f(x)+2x=x+(b+2)x+c
2因为g(x)为偶函数,所以g(x)对称轴x=−2b+2=0,得b=−2. 2·············································································· 4分 所以f(x)=x−2x+c ·方案一:选条件①.
······················································· 5分 因为f(x)的对称轴为x=1,且开口向上 ·
···························································· 7分 所以当x=−2时,f(x)取得最大值5·
······················································· 9分 所以f(−2)=4+4+c=5,解得c=−3 ·
高一数学试题答案 第1页(共6页)
·············································································· 10分 所以f(x)=x2−2x−3 ·方案二:选条件②.
因为f(x)≤0的解集为1,且函数f(x)图象开口向上,
·································································· 7分 所以f(x)有且仅有一个零点为1 ·
············································································· 8分 所以f(1)=1−2+c=0 ·
································································································ 9分 所以c=1 ·
················································································ 10分 所以f(x)=x2−2x+1·方案三:选条件③.
因为x1,x2为方程x2−2x+c=0的两根. 所以=4−4c0,即c1.
·············································································· 7分 且x1+x2=2,x1x2=c ·
··············································· 8分 所以x1+x2=(x1+x2)−2x1x2=4−2c=10 ·
······························································································ 9分 解得c=−3 ·
·············································································· 10分 所以f(x)=x−2x−3 ·
18.本题考查三角函数的图象和性质等知识;考查推理论证能力和运算求解能力;考查数形
结合,化归与转化等数学思想. 本题满分12分. 解:
(1)由图可知,
2222Tπππ=−−= ····························································· 1分 4362····························································································· 2分 解得T=2π ·因为T=2π············································································· 3分 ,所以=1
所以f(x)=sin(x+).
ππ−,0sinfx··································· 4分 因为()的图象过点,所以−+=0 ·66所以−ππ+=kπ,kZ得=kπ+, 66因为ππ············································································ 5分 ,所以= ·
26高一数学试题答案 第2页(共6页)
所以f(x)=sinx+π············································································· 6分 ·6π················································· 8分 ·6(2)解法一:由题意,g(x)=sin2x+令t=2x+ππ13π ············································· 9分 ,因为0xπ,所以t66611π5π13π,得sint=,得t=,,. 22666由g(x)=即2x+ππ5π13ππ=或或,解得x=0,,π. 666631π················································ 12分 在0,π的解为0,,π ·
231πππ5π,得2x+=2k1π+,k1Z或2x+=2k2π+,k2Z 26666所以方程g(x)=解法二:令g(x)= ··············································································································· 8分 解得x=k1π,k1Z或x=k2π+π················································· 10分 ,k2Z ·
3因为x0,π,所以x=0,
π,π 3所以方程g(x)=1π················································ 12分 在0,π的解为0,,π ·
2319. (教材P161.12)本题考查函数单调性的证明及其应用,对数函数的图象与性质,对
数不等式的求解等知识,考查分类讨论、化归与转化等思想.
··············································································· 1分 解:(1)f(x)是减函数 证明如下:x1,x2R,且x1x2 则f(x1)−f(x2)=11− ·································································· 2分 x1x21+21+22x2−2x1 ································································· 4分 =(1+2x1)(1+2x2)·························· 5分 因为x1x2,所以2x2−2x10,又因为1+2x10,1+2x20 ·
高一数学试题答案 第3页(共6页)
所以f(x1)−f(x2)0,即f(x1)f(x2).
····················································································· 6分 所以f(x)是减函数 (2)由题意得f(loga2)1························ 7分 =f(1),由(1)知f(x)是减函数 ·
3·························································································· 8分 所以loga21 ·
··································· 10分 当a1时,由loga21=logaa,得a2,所以a2 当0a1时,由loga21=logaa,得a2,所以0a1. 综上所述:a的取值范围为(0,1)····················································· 12分 (2,+) ·
20. (教材P255.22)本题考查三角函数图象与性质,诱导公式. 考查运算求解,推理论
证能力. 考查化归与转化,数形结合等数学思想. 本题满分12分. 解:(1)f(x)=311··············································· 2分 sin2x+cos2x++m ·
2221=sin2x+++m ·························································· 3分
62当2x+πππ=−+2kπ,kZ,即x=−+kπ,kZ时,
36215=−3,得m=− ······················································ 4分 22f(x)的最小值为m−fx=sin2x+因为()−2,令z=2x+,
66函数y=sinz−2的单调递减区间是2kπ+π3π,2kπ+,kZ ······················· 5分 22且由2kπ+ππ3ππ2π2x+2kπ+,得kπ+xkπ+ 26263π2π,kπ+,kZ ······························· 6分 63所以函数f(x)的单调递减区间是kπ+(2)由题意得:asinx+sin2x+π−20在(0,π)上恒成立 2················································· 7分 所以asinx+cos2x−20在(0,π)上恒成立 ·
高一数学试题答案 第4页(共6页)
················································ 8分 所以asinx−1−2sin2x0在(0,π)上恒成立 ·
································································ 9分 因为x(0,π),所以sinx(0,1 ·
2sin2x+11所以a在(0,π)上恒成立 =2sinx+sinxsinx又因为2sinx+11π3π22,当且仅当2sinx=,即x=或时,等号成立.
sinxsinx44··································································· 12分 所以a的取值范围为−,22 ·
21.(教材P156.11)
本题考查指数函数模型应用,对数运算等知识;考查运算求解和推理论证等能力、应用意识与创新意识;考查化归与转化、函数与方程等数学思想.本题满分12分. 解:(1)记2017−2019年全球年产生数据量的年增长率分别为p1,p2,p3 依题意得p1=()263341··············· 3分 −10.44,p2=−10.27,p3=−10.24 ·
182633所以p=1·························································· 4分 (0.44+0.27+0.24)0.32 ·
3··························································································· 5分 又因为a=18 ·
··············································· 6分 所以f(t)=18(1+0.32)=181.32(tN) ·
tt(2)设从2020年起,经过n年我国的数据量将达到全球数据总量的30%,
············································ 7分 由(1)知2020年全球年产生数据量为181.324 ·依题意得0.2181.32(4)(1+0.5)n181.32n+40.3 ···································· 9分
1.5所以1.32即nlogn3 233lg3−lg20.477−0.3010.1762====3.2
1.52lglg3−lg2−lg1.320.477−0.301−0.1210.0551.32lg1.51.32 ··············································································································· 11分
······················ 12分 答:估计到2024年,我国的数据量将达到全球数据总量的30%. ·
22.本题考查函数单调性与最值、零点与基本不等式等基本知识;考查推理论证能力、运算求解能力;考查化归与转化、函数与方程、分类讨论等数学思想方法. 解:(1) 因为y=a(a1),y=−x1在(0,+)上单调递增.............................................. 1分 x高一数学试题答案 第5页(共6页)
1(a1)在(0,+)上单调递增 ................................................................. 2分 x12所以f(x)在[1,2]的最大值为f(2)=a− ....................................................................... 3分
2172所以a−=,所以a=2 ................................................................................................... 4分
221x(2)证明:因为x(−,0),所以f(x)=a−0
x1x所以f(x)=a−在(−,0)不存在零点 ............................................................................. 5分
x1x由(1)得f(x)=a−在(0,+)上单调递增,
x所以f(x)=a−x11又因为f()=aa−a0,f(1)=a−10,
a所以f(x)在(0,+)上有唯一零点x0,且x0(,1) ......................................................... 7分
0方法一:因为a−1ax1=0,所以x0ax0=1,logax0+x0=0 .......................................... 8分 x011x+2, 因为x0(,1),所以0xa0所以2−x0由x0ax011=−logax0=x0 .............................................. 10分 ,loga(2−x0)logax0x0=1,loga(2−x0)x0
2x0所以loga(2−x0)+x0−2x0ax0+x02−2 ................................................................... 11分
2因为0x01,所以x0+x02,得证. ........................................................................ 12分
x0方法二:因为a−1=0,有x0ax0=1 x02x02=loga(2−x0)+x0−2 ..................................................... 8分
所以loga(2−x0)+x0−2x0a因为g(x)=loga(2−x)在(,1)单调递减, 所以loga(2−x0)loga(2−), 当a1时,a+1a1a112,所以2−a aa有loga(2−)logaa=1,即loga(2−x0)1 ................................................................ 10分
1a高一数学试题答案 第6页(共6页)
2因为h(x)=x2−2在(,1)单调递增,所以x0−2−1 .................................................. 11分
1a所以loga(2−x0)+x0−20,得证 .................................................................................. 12分
2高一数学试题答案 第7页(共6页)
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