PHoNG GrAo DUC va oAo rno olEN csAu oE xrBivr rRA rrEN rHUc rRudc rY rHr vAo r0p t0 THpr NAnn Hec zots-20r6 MOn thi: TOAN Thdi gian ldm bdi 120 phrit CAu 1(3,0 didm). Cho bidu thftc .q a) Tim didu kiOn cl&ra xdd, ,qc6 b) Tinh giStrt cria bidu thtc,q khi x = 9 . c) Tim tdt cit cdc gt6 tri cfia x dd, ,q <0. Cau 2 (I ,5 didm). Cho phuong trinh bAc hai dn *: x' - x * m = 0 a) Gi6i phuong trinh v6i m = -6 b) Tim m dd phuong trinh c6 hai nghiOm phAn biOt th6a m5n: lx,-xrl=2 CAu 3 (1,5 didm) Hoc sinh lcrp 9B cfia mot trudng THCS quy0n g6p trng h6 hoc sinh nghbo huyOn Tuong Duong. Ndu m6i em quyOn g6p duoc 3 quydn v& thi tdng sd v6 quyOn g6p duoc wgt qu6 mrlc du dinh ld 12 quydn. Ndu m6i em quyOn g6p du-o. c 2 quydn v& thi tdng sd vO quy0n g6p duoc it hon mrlc du dinh1d,22 quydn. H6i lorp 9B c6 bao nhiOu hoc sinh vd sd quydn v& du dinh quyOn g6p ld bao nhiOu? Qi^ !!3,5 didm) cho tam gi6c vudng cAB nQi tidp duong trdn tdm o(a= 900;cB<cA).Tia phAn gi6c c:iua g6c C c6t dudng trdn tai didm rhrl hai le D, CD c6t AB rai E . a) Chirng minh: frD=frD; b) Chrrng minh DB2 = DC.DE ; c) Tron tia cB la'y didm M sao cho CM = CA. Tt M k6 tia Mx//cA cit tia cD tai N, AN c6t duong trdn (o) r4i F . chfng mi4h 3 didm o,c, F thing hdng; d) Goi I td giao didm cria BD vI MN. Ctrung minh AI h tidp tuydn cira duong trbn tAm O. Qu 5(0,5 didm). Cho a,b,c le dO dAi 3 c4nh ctta mdt tam gi6c vd, a.b.c =t . Chrrng minh rang: +-* 1-*-f > ab+bc+ca. o+b-c b+c-a c-fa-b Hdt PHoNG GIAo DUC vA DAo rAo otEN cHAu HUoNG tAN cnAu oi rrdrvr rnn xrfN THUc rRuoc xi rHl vAo lop l0 THPT MOn thi: TOAN CAU Ndi dung Diim Ia Didu kiOn: x> 0;x + 4; 0,5 1,0 0,5 0,5 0,5 /l- n- J*,;J; _) d;;;j 2 (J; - 4.di +2) 1.b Jq -t L = 7 ,' ,1 = 7- = "le -2 ) 1 1.c t:1 . v, - r fl=- - 1U ^lx -2 fJi-r'o [Ji-r'o <>i- ;l lJx-2<0 lJr'-2>0 timduoc: 7<x<4 2.a rm=-6, phuong trinh tr&thdnh : x2 -x-6=0; 0,25 0,25 + Tinh duoc L=25 +Tim duoc: xt:3,x2 = -2 0,5 0,25 0,25 2.b Dd phuong trinh c6 hai nghiO khi d6 PT c6 hai nshiOm m phAn bi0t thi A =1- 4m> 0 o rr.! A phAn biot th6a mdn: {x' + x' =1 lxt.X2 = m = (". -*r)' =(x, * xr)t'4x,xr:l-4nt =lt, - ,.1=,ltJm=2, tim duoc m:-0,75 3. + tr9i;-18 so hoc sinh cria l6p 98, y ld so quydn v& du dinh quy0n g6p( x;y ld' c6c sd nguy€n duong) + Ndu m6i em g6p 3 quydn v6 thi sd vd g6p duoc cua ldp ld 3x g_6p- dugg "qqe lOp Ii, ?r 0,5 0,5 ; so hoc sinh l6p 98 le 34 em, sd luong v& du dinh quyOn g6p ld 90 quydn. l;:i4 €< lv=90 0,5 4. a) Vi CD la tia phAn gi6c ciatr-a = 6)=68=7jD:EID ,': " -" " '- ''-"j'1 "'-'-"' b) ABCD_ dQ-qe da+g y6l LEpD (g,g) DB DD - 'L e DBz = DC.DE DQ. DB ) -^9W +cj!("c:s,c) vd M-N/C-A = e vw = eAN = lv = CF la dudng k(nh gir"e (O)- -c.,o_,f thing- h-flI: d) LCAD = LCMD (c.g.c) = DA = DM, 6)=58 =DA = DB,=DB = DM = L,DBM cdn - 6rfu * rEfu = eoo = BMD * 6it = 6it * i6it = 6tfu = 6it = LMDI can(dinh D) = DI = DM =4 didm A,B,M,I ndm trOn dudng trdn dudng kinh BI =6h -6fu =p=- ll lol =_AI l+-tisp_lsyen g_9r d_{gps ggt,t?$ o, Hinh v6 dfns I DI=DM=DA=DB 0_f 0-,5 . 0,5 0,5 0,5 0,5 0.5 . _- r | 4 Ta c6 x;y ld,hai sd duong thi : ' > L t x y x+y 1 1 4 2. I 1 - 4 2 | | 4 2 +-2 == =i +-j - 2;= =; - ^ r+ ^, ^ ^'-;=;l )( | * 1 * l -)>2(l*l* !)=2.o0*oln'o =2(ab+bc+ca) t\;+b-c-i*c-ac+a-b' 'Qbcabc 1 1 r- 1 >-ab+bc+ca; dA'u "=" xdYrakhi a=b c' 1 *. Chrt y: - Hoc sinlt gidi cdch khdc dfing cho didm t,i da - - HQc shhLhAng vd hinh kh1rtg chd'm didm cdu 4' . quyOn g6p duoc 3 quydn v& thi tdng sd v6 quyOn g6p duoc wgt qu6 mrlc du dinh ld 12 quydn. Ndu m6i em quyOn g6p du-o. c 2 quydn v& thi tdng sd vO quy0n g6p duoc it. rno olEN csAu oE xrBivr rRA rrEN rHUc rRudc rY rHr vAo r0p t0 THpr NAnn Hec zots-20r6 MOn thi: TOAN Thdi gian ldm bdi 120 phrit CAu 1(3,0 didm). Cho bidu thftc .q a) Tim didu kiOn. Mx//cA cit tia cD tai N, AN c6t duong trdn (o) r4i F . chfng mi4h 3 didm o,c, F thing hdng; d) Goi I td giao didm cria BD vI MN. Ctrung minh AI h tidp tuydn cira duong