厦门市2015-2016学年度第一学期高二年级质量检查 数学文科及参考答案评分标准

厦门市2015—2016学年度第一学期高二年级质量检测数学（文科）参考答案一、选择题：（本大题共12小题，每小题5分，共60分）12.设11(,)A x y 、22(,)B x y ，由2(1)y x y k x ⎧=⎨=-⎩得222(21)0k x k x k -++=，即121x x ⋅=.又211222y x y x ⎧=⎪⎨=⎪⎩，∴21212()1y y x x ⋅=⋅=即121y y ⋅=-，∴12120x x y y ⋅+⋅=， 即OA OB ⊥.设33(,)C x y 、44(,)D x y ，直线OA ：1y k x =，直线OB ：2y k x =，则121k k ⋅=-.由21y x y k x ⎧=⎨=⎩得00x y =⎧⎨=⎩或21111x k y k ⎧=⎪⎪⎨⎪=⎪⎩即21111(,)A k k ，同理22211(,)B k k .由221(2)4x y yk x⎧-+=⎨=⎩得00x y =⎧⎨=⎩或211214141x k k y k ⎧=⎪+⎪⎨⎪=⎪+⎩即1221144(,)11k D k k ++， 同理2222244(,)11k E k k ++.∴OA =，OB = OD =OE =∴221122221211111(1)(1)2(1)(1)12116161642OABODEk k OA OB S k k k k S OD OE ∆∆++++++====≥.二、填空题：（本大题共4小题，每小题5分，共20分）13．,x R ∀∈21xx ≠+； 14．815y x =- ； 15．3λ<； 16．20． 三、解答题：（本大题共6小题，共70分．解答应写出文字说明，或演算步骤）． 17．本题考查等差、等比数列的通项公式及前n 项和公式等基础知识，考查运算求解能力. 考查化归与转化思想、方程思想．满分10分.【解析】(Ⅰ)设等比数列{}n a 的首项为1a ，公比为q .364,32a a ==，解得12,1q a ==， ··································· 3分 1112n n n a a q --∴==. ······················································· 4分(Ⅱ)设等差数列{}n b 的首项为1b ，公差为d .4145b =+=，21b =，∴4224,d b b =-=即2d =，11=-b ， ·········· 6分∴23n b n =-， ··································································· 7分 ∴数列{}+n n a b 的前n 项和为11()(1)12n n n n b b a q T q +-=+-12(123)122n n n --+-=+- ···························································· 9分 2221n n n =+-- . ···································································· 10分18．本题考查正弦、余弦定理和解三角形等基础知识，考查运算能力、思维分析能力，考查化归与转化思想、方程思想、分类讨论思想．本题满分12分．【解析】(Ⅰ) 由正弦定理，结合条件：sin (sin sin c C a A b B ⋅⋅⋅＝＋(可得，2(a c b a b -⋅=⋅＋( ································· 2分22a b =＋22b b a =＋．222b a c ∴＋-， ··········································································· 4分2222a c ab b ==＋-，即 cos C =，0C π<<，6C π∴=． ········· 6分(Ⅱ)法一：由余弦定理，结合条件：32=a ，2c =, 又由(Ⅰ)知6C π=，可得 2222cos c a b ab C =+-，∴24122b =+-⋅，即2680b b -+=， ··········· 8分 解得2b =或4b =，经检验，两解均有意义． ··········· 11分综上，ABC ∆周长为4+6+ ··· 12分 法二：由正弦定理，结合条件：32=a ，2c =,又由(Ⅰ)知6C π=，可得1sin 2sin 2a C A c === ············································ 7分 a c > A C ∴> 3A π∴=或23π，从而2B π=或6π. ······························· 8分当2B π=时，ABC ∆为直角三角形，4b ∴=，ABC ∴∆周长为6+ 当6B π=时，ABC ∆为等腰三角形，2b c ∴==，ABC ∴∆周长为4+ 11分综上，ABC ∆周长为4+6+ ··· 12分 19．本题考查抛物线定义，直线与抛物线关系，考查运算求解能力．考查化归与转化思想、数形结合思想、分类讨论思想．本题满分12分．【解析】(Ⅰ)由题意得，M 到点（3,0）的距离与到直线3x =-的距离都等于半径，由抛物线的定义可知， C 的轨迹是抛物线，设其方程为22y px =，32p=， ∴M 的轨迹方程为212y x =． ··································· 3分 (Ⅱ)法一：显然斜率不为0，设直线l ：6x ty =+，11(,)A x y 、22(,)B x y2AP PB =，∴1122(6,)2(6,)x y x y --=-，∴122y y =-， ···················· 6分 由2126y x x ty ⎧=⎨=+⎩得212720y ty --=∴12121272y y t y y +=⎧⎨⋅=-⎩， ································ 8分又122y y =-，∴ 121260.5y y t =⎧⎪=-⎨⎪=⎩或121260.5y y t =-⎧⎪=⎨⎪=-⎩ ， ······································ 10分∴ 直线l 的方程是212y x =-或212y x =-+． ·································· 12分法二：①当直线l 的斜率不存在时，直线l ：x =6，显然不成立． ················ 4分 ②当直线l 的斜率存在时，设直线l ：(6)y k x =-，11(,)A x y 、22(,)B x y ，2AP PB =， ∴1122(6,)2(6,)x y x y --=-，∴12218x x +=， ··············· 7分 由212(6)y x y k x ⎧=⎨=-⎩得222212(1)360k x k x k -++=，∴21221212(1)36k x x k x x ⎧++=⎪⎨⎪⋅=⎩， ·· 9分 ∴121232x x k =⎧⎪=⎨⎪=±⎩······················································································ 11分 ∴直线l 的方程是212y x =-或212y x =-+． ·············· 12分 20.本题考查等差等比数列的定义、性质，等差等比数列的综合运用，及求数列的前n 项和，考查运算求解能力．考查化归与转化思想、方程思想．本题满分12分. 【解析】（I ）13,,n n a a +成等差数列，1123,32(3),n n n n a a a a ++∴=+∴-=- ··· 2分即11323n n n n b a b a ++-==-，又131a -=，······································· 4分 ∴{}n b 是首项为1，公比为2的等比数列. ··································· 5分 （II）{}n b 是首项为1，公比为2的等比数列,∴132n n n b a -=-=，即123n n a -=+. ··················································· 7分又22log (26)log 2n n n c a n =-==, ··············································· 8分212111111()(21)(21)22121n n c c n n n n -+∴==--+-+, ······································· 9分 13352121111n n n T c c c c c c -+∴=+++111111(1)23352121n n =-+-++--+ ················································· 10分 111(1)2212n =-<+.······························································ 12分 21．本题考查解二次不等式、利用二次函数和基本不等式求最值，考查数学建模能力，信息处理能力和运算能力，考查化归转化思想、数形结合思想、函数方程思想和分类讨论思想．本题满分12分． 【解析】（Ⅰ）设该企业计划在A 国投入的总成本为()Q x （亿元）， 则当010x ≤≤时，25()1644x x Q x =++，依题意：25()51644x x Q x =++≤, ············································· 1分 即24600x x +-≤，解得106x -≤≤, ··················· 3分 结合条件010x ≤≤，06x ∴≤≤.················· 4分 （Ⅱ）依题意，该企业计划在A 国投入的总成本为25,010,1644()42,10.5x x x Q x x x x ⎧++≤≤⎪⎪=⎨⎪+->⎪⎩5分 则平均处理成本为251,010,()1644421,10.5x x Q x x x x x x ⎧++≤≤⎪⎪=⎨⎪-+>⎪⎩·········· 6分 (i)当010x ≤≤时，()51116444Q x x x x=++≥=，当且仅当5164x x =， 即x =min()Q x x ⎛⎫= ⎪⎝⎭. ·············· 8分(ii) 当10x >时， 22()42119914()520100Q x x x x x =-+=-+, ∴当1120x =即x =20时，min ()9911004Q x x ⎛⎫=> ⎪⎝⎭. ············· 10分 ∴当x =min()Q x x ⎛⎫= ⎪⎝⎭. ···················· 11分 答：（Ⅰ）该工艺处理量x 的取值范围是06x ≤≤.（Ⅱ）该企业处理量为万吨时，才能使每万吨的平均处理成本最低，平均处理成本亿元. ··································································································· 12分22．本题考查曲线的轨迹方程、直线和椭圆的位置关系、弦长公式、定点定值问题等知识，考查运算求解能力，探究论证能力．考查化归与转化思想、数形结合思想、函数方程思想、分类讨论思想．本题满分12分． 【解析】（I ）设M 的坐标为(,)x y ，则1A M k x =≠，2A M k x =≠，12=-(x ≠， ········································· 1分化简得点M的轨迹方程是221(2x y x +=≠． ····································· 3分 （Ⅱ）①当直线l的斜率不存在时，PQ = ···································· 4分②当直线l 的斜率存在时，设11(,)P x y ，22(,)Q x y ，直线l 的方程为：(1)y k x =-，则2212(1)x y y k x ⎧+=⎪⎨⎪=-⎩得，2222(21)4220k x k x k +-+-=，∴212221224212221k x x k k x x k ⎧+=⎪⎪+⎨-⎪⋅=⎪+⎩， · 6分222)1)2121k PQ k k +===+>++ ·· 7分 综上所述，PQ． ··············· 8分（Ⅲ）假设点N 存在，由椭圆的对称性得，则点N 一定在x 轴上，不妨设点(,0)N n ，当直线l 的斜率存在时，由（Ⅱ）得212221224212221k x x k k x x k ⎧+=⎪⎪+⎨-⎪⋅=⎪+⎩， ∴22121212122(1)(1)[()1]21k y y k x k x k x x x x k ⋅=--=⋅-++=-+，11(,)NP x n y =-，22(,)NQ x n y =-，∴21212121212()()()NP NQ x n x n y y x x n x x n y y ⋅=-⋅-+⋅=⋅-+++⋅∴22222222222224(241)221212121k k k n n k n NP NQ n n k k k k --++-⋅=-+-=++++ ·· 10分对于任意的k ，0NP NQ ⋅=，∴22241020n n n ⎧-+=⎪⎨-=⎪⎩， ······························· 11分方程组无解，∴点N 不存在．综上所述，不存在符合条件的点N ． ············································· 12分。