北京市第十三中学2020-2021第一学期期中考试参考答案

北京市第十三中学北京市第十三中学2020-2021学年度学年度九年级数学九年级数学期中测试参考答案期中测试参考答案一．一．选择题选择题题号题号12345678答案答案BCACBDDB二．填空题二．填空题题号题号910111213141516答案答案22(3)2yx=−+422m<121,-3832,23三．解答题三．解答题32=2-2+33+2-1----------422=3-2+33+2-1=43-1------------------------517.解：原式分分18.．（1）证明：∵CE=CD，∴∠CDE=∠CED.∴∠ADB=∠CEA.∵∠DAC=∠B，∴△ABD∽△CAE.·····························································3分（2）解：由（1）△ABD∽△CAE，∴AEBDACAB=.∵AB=6，AC=92，BD=2，∴AE=23．·············································································5分19.解：（1）把M（a，2）代入32−−=xy，得322−−=a，∴a＝－2.5.……………………………………………………………………1分把N（1，b）代入32−−=xy，∴b＝－5.……………………………………………………………………2分把M（－2.5，2）代入xky=，得5.22−=k，∴k＝－5.……………………………………………………………………3分（2）P（0，1）或P（0，－7）.…………………………………………………………5分