loading北京市平谷区2019年中考统一练习（一）
数学试卷参考答案及评分标准 2019.4
一、选择题（本题共16分，每小题2分）
题号 答案 1 C 2 C 3 B 4 D 5 B 6 A 7 A 8 B 二、填空题（本题共16分，每小题2分）
9．正方； 10．x>-1； 11．甲； 12．答案不唯一，如BD=DC； 13．
?2.5x?2y?2022； 14．a?b??a?b??a?b?； 15．23； 16．(4,0)．
x?y?11?20三、解答题(本题共68分，第17-21题，每小题5分，第22-27题，每小题6分，第28题7分)解答应写出文字说明、演算步骤或证明过程. 17．（1）如图； ·····························································································1
ACPOBD （2）同位角相等，两直线平行； ································································3
等边对等角． ··················································································5 18．解：原式=2?3?1?23?3?1=0． 2219．解：由①得x<3 ，由①得x+1>2， x>1．∴1 (2) ∵x??k?3?2?0，∴方程总有两个实数根． ??k?1??2?k?3?2，∴x1??1，x2?2?k． ························4 ∵方程有一个根为正数，∴2?k?0k?2． ······································5 21．（1）k=4； ·····························································································1 （2）①1个； ·························································································2 ②当直线AB经过点A（2，﹣2），（0,1）时区域W内恰有1个整点，∴a?1． 2当直线AB经过点A（2，﹣2），（1,1）时区域W内没有整点，∴a=1． ·····3 ∴当 1········································5 ?a?1时区域W内恰有1个整点． · 222．（1）证明：∵AB=AC，点D是BC边的中点，∴AD⊥BC于点D． ·····················1 ∵AE∥BC，CE∥AD，∴四边形ADCE是平行四边形． ·····················2 ∴平行四边形ADCE是矩形． ······················································3 A（2）解： 过点E作EF⊥AC于F．∵AB=10，∴AC=10． ∵对角线AC，DE交于点O，∴DE=AC=10．∴OE=5． ∵sin∠COE= E4，∴EF=4∴OF=3．∵OE=OC=5，∴CF=2． 5OBFDC∴CE=25． 23．（1）如图； ····························································································1 1