rs PHoNG GrAo DUC vA ono rAo oGN cuAu A oE rnr cHeN Hgc srNH crdr HUyfr'N, Lop 9 voNG rr NAM HQC 2013-2014 ivtON: Todn ( Thdi gian lhm bei 150 phrit) Chul(4,O didd. Gthi cdc phuong trinh sau: a. 3h+x+J-i=2; b. zJ*-t+Jz-* =zJi. Cdu 2(4,0 didm). Gihi cdc hO phuong trinh sau: ^ l* +2xy-3x-3y-4=0. a. i , l*-y-5=0 b. [w = Y' +^l l1-(x+l)' i J' /I = (y +l)2 CAu 3: (4,0 didd. a. Tim gi6tnnh6 nhdt cria bidu thrlc: b. Cho x,t,z le dQ dei 3 canh cira mot tam grdc, chrlng minh rang: godi dudtng trbn thfing d khOng di qua O cit (O) tai B vd C(B nim gifra A (O) tai B vd C c5t nhau tai E. TU E ke EH vuOng g6c vdi cung nh6 BC tai G. Goi D ld giao didm cira EO vd BC. a. Chung minh OH.OA = OD.OE; - b. Chtnrg minh AG lA tidp tuydn cira dudn,g trdn tAm O. Ci 5(4,0 didm). Cho hai ducrng trdn tdm O vd tam O/ tidp xric ngodi tai I. K6 tidp tuydn chung ngodi vdi (O) tai P vd vdi (O/) tai Q, cit ridp tuydn chung rrong It tai K. K6'c6c duong kfnh POP vd QC/Q/. I a. Chrrng minh ba didm P, I, O thing hdng vd ba didm Q, I, P cfrng thing hdng; b.jGoi S 1)r trung didm cira PQ/. Chung minh rang duirng thing PQ ld tidp \-/ tuydn cira dudng trdn ngoai tidp tam gii{c SOO/. tAm O. Qua A k6 duong vd C). Cr{c tidp tuydn vdi AO( H ndm trOn AO) c6t Hdt . HUyfr'N, Lop 9 voNG rr NAM HQC 20 13 -20 14 ivtON: Todn ( Thdi gian lhm bei 150 phrit) Chul(4,O didd. Gthi cdc phuong trinh sau: a. 3h+x+J-i =2; b. zJ*-t+Jz-* =zJi. Cdu 2( 4,0 didm) a. Chrrng minh ba didm P, I, O thing hdng vd ba didm Q, I, P cfrng thing hdng; b.jGoi S 1)r trung didm cira PQ/. Chung minh rang duirng thing PQ ld tidp -/ tuydn cira dudng. didm). Gihi cdc hO phuong trinh sau: ^ l* +2xy-3x-3y-4=0. a. i , l*-y-5=0 b. [w = Y' +^l l1-(x+l)' i J' /I = (y +l )2 CAu 3: (4,0 didd. a. Tim gi6tnnh6 nhdt cria