Đề thi chọn học sinh giỏi lớp 9 - Môn: Toán - Bẳng A

Nội dung text: Đề thi chọn học sinh giỏi lớp 9 - Môn: Toán - Bẳng A

1. i' Tt+cs Vil, L3: GIol LoP e so cnsor NcuD lN xV rHt cHQN HQC THI Ndm Hgc 20.13-2014 on csiNs rstJc Mdn Thi: TOAN - Bing A Thoi gianr 150 phut (khong kA thoi gian giao d€1 CAu 1 (4.0c1i6m). chia het cho l0 a, Chung minh rdng t6n t4i s6 tq nhidn frsao cho 20130 -l b. Tim mgi sO nguyOn x sao t1's )c2+28 ld s6 chinh phuong Cdu 2 (6.0 tli6m). a. GiAi phuong trinh: ^t+r'-;y1: -2'[7 - -+1 =9x-3 =t b. ciai hQ phuong trinh: \''l':*:I x zxY-Y .r'::' =z Cdu3(3.0eli6m).ChocdcsdthucducrnEX,l'zth6amlnxy+yztzx=t' r- rnin c6a P: ::-n * Tim x+y y+z z+x nho hon curtg CBD' Gqi /J ld giao dicnt rron tai c, D(c nam gioa M vd D) cung CAD gba AB vsi OM. a. Chung minh 5Eb = zSnc BA o K' Chu'ng minh KC vi KD la tiilr b, Tir o ke tia or vu6ng goc voi cD cattia tuy6n cua dudng tron O lu0rr co clQ dai bang l 'Chung nrinh rAng C6u 5 (2.0 rli6m). Cho ducrng gAp khuc khep l<in gAp khuc dti hinh trdn c6 b6n kinh p: chua todn b0 cluirng t6n t4i mQt 4I Sd b6o danh . Ho v2r tOn thi sinh
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