四川省巴中市高三数学上学期 零诊 考试试卷 文(PDF)答案 四川省巴中市届高三数学上学期 零诊 考试试卷 文(PDF) 四川省巴中市届高三数学上学期 零诊 考试试卷 文(PDF)VIP免费

共5页第1页巴中市高2018级“零诊”考试文科数学参考答案及评分细则一、选择题（每小题5分，共60分）题号123456789101112答案DBDAABCCBCBA二、填空题（每小题5分，共20分）13.0000,sinxxx≥14.315.3216.②③④三、解答题（共70分）17、解：（1）由1122nnnaa变形得：12211nnnnaa····························································3分又21a，故112a··························································································4分∴数列{}2nna是以1为首项1为公差的等差数列。·················································5分（2）由（1）知：nabnnn2··················································································6分∴11111(1)1nnbbnnnn············································································8分∴1223111111111(1)()()2231nnbbbbbbnn·······························10分=1111n···························································11分∴122311111nnbbbbbb·········································································12分18、解：（1）这一天小王朋友圈中好友走路步数的平均数6014010060201822610141822309.04400400400400400400400千步所以这一天小王400名好友走路的平均步数约为9.04千步。····································3分（2）因频率约等概率可得()19.048(60140100)0.5654004AP所以事件A的概率约为0.565·············································································7分（3）健步达人非健步达人合计40岁以上15050200不超过40岁50150200合计20020040022224400(15050)10010.828200K所以有99.9%以上的把握认为健步达人与年龄有关。··············································12分19、解：（1）证明：共5页第2页方法一取AB的中点M，连结1,DMMB（如图） ,ADDCAMMB∴1//,2DMBCDMBC················································································1分由棱柱的性质知：1111//,BCBCBCBC································································2分又11BEEC∴11//,DMBEDMBE·················································································3分∴四边形1DMBE为平行四边形∴1//DEMB·································································································4分 1MB平面11ABBA，DE平面11ABBA∴//DE平面11ABBA·····················································...