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《2013~2014学年度第二学期期中考试数学答案.doc》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、2014年九年级期中考试参考答案一、选择题:本大题共10小题;每小题3分,共30分。下列各题都有代号为A、B、C、D的四个结论供选择,其中只有一个结论是正确的。1.C2.C3.B4.B5.C6.C7.A8.C9.C10.D二、填空题:本题共8小题;每小题3分,共24分。不需要写解答过程。11.x≥12.13.414.1215.16.k≤且k≠017.6418.4三、解答题:本大题共10小题,共96分。解答时应写出文字说明、证明过程或演算步骤。19.(本题满分10分)计算:(1)解:原式=·············4分==4·············5分(2)解
2、:原式=············7分=············9分=············10分20.(本题满分8分)解:原式=············2分=············4分=············6分=············7分取x=2(x≠0或±1),原式=1············8分21.(本题满分8分)解:①+②得,∴,············3分代入①得∴············6分∴············8分22.(本题满分8分)解:(1)∵四边形ABCD是平行四边形,∴AB=DC.·············1分∵E,F为BC
3、上两点且BE=CF,AF=DE,∴BF=CE,·············3分∴△ABF≌△DCE(sss).·············4分(2)∵△ABF≌△DCE,∴∠B=∠C.·············5分∵在平行四边形ABCD中,AB∥CD,·············6分∴∠B+∠C=180°,∴∠B=∠C=90°,·························7分∴四边形ABCD是矩形.·············8分23.(本题满分8分)解:(1)将(-1,0),(0,3)代入得解得·············1分∴.·············4分(
4、2).·············6分(3),·············7分∵≤x≤2,∴当x=1时,y的最大值为4.············8分24.(本题满分8分)(1)证明:△=·············1分==≥0·············3分∴该一元二次方程总有两个实数根.·············4分(2)解:动点P(m,n)所形成的函数图象经过点A(4,5).·············5分理由:∵,,∴.·············6分∵当时,,·············7分∴动点P(m,n)所形成的函数图象经过点A(4,5).···········
5、··8分25.(本题满分8分)解:(1)连接OD.∵OA为半径的圆弧与BC相切于点D,∴OD⊥BC.·············1分∴∠ODB=∠C=∠ODC=90°,∴OD∥AC,∴∠ODA=∠CAD,·············2分又∵OA=OD,∴∠ODA=∠OAD.ABCODEH∴∠CAD=∠OAD,·············3分∴AD平分∠BAC.……………………4分(2)过O作OH⊥AC于H,∴.·············5分∵OH⊥AC,∴∠OHC=90°,∵∠ODC=90°,∠C=90°,∴四边形ODCH为矩形,·············6分∴OH
6、=DC=.·············7分∴在Rt△AHO中,圆弧的半径OA=.………………8分26.(本题满分12分)解:(1),∴z与x之间的函数解析式为;·····3分(不化简不扣分)(2)当时,·············4分解得·············6分因此,当销售单价为28或40元时,厂商每月获得的利润为440万元······7分(3)由题意,得18(-2x+100)≤540·············8分解得x≥35·············9分配方得∴当x≥34时,z随x的增大而减小·············10分∴当x=35时,z最大为510万
7、元当销售单价为35元时,厂商每月获得的利润最大,为510万元.············12分27.(本题满分12分)(1)证明:连接CD,过点D作DG⊥AC于点G,DH⊥BC于点H,∴∠DGE=∠DHF=90°.·············1分ABCDEF图1GH∵AC=BC,点D为AB中点,∴CD平分∠ACB,∴DG=DH.·············2分∵∠ACB=120°,∠EDF=60°,∴∠DEC+∠DFH=180°,∵∠DEC+∠DEG=180°,∴∠DFH=∠DEG,·············3分∴△DGE≌△DHF,·············4分∴
8、DE=DF.·············
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