so cn-or HA riNn ps cHiNu rHrlc Bdi 1. Rtit ggn: oe rHr KHAO sAT cHAr Lr-IONG HQC KY r, LOp 9 NAM HQC 2014 - 20rs M6n: TOAN (Thdi gian ldm bdi: 90 philt) a. P:2Jn -oJf 6 -D' . 11 b. o=_;_____. :,l -lz I .,12 +l Bdi2.Chobi€uthric,F:(S .gl '-J voir)0, x+9. [ /x+3 Jx-3) Jx a. Rut ggn bitiu thric F. ,1 b. Tim x bi6t F =;. Bni 3. Trong rn{t ph[ng to? d0 O,*y cho duong thdng . d c6 phucrng trinh: y =(m-2)x+3m+6 (m +2)Timm d0 duong thdng r/di qua di6m M(-l; 3). Bni 4. Cho duong trdn (O;R) vd H ld mQt diiSrn tr€n tludng trdn. K6 ducrng thhng d lit ti6p tuy6n cria dudng trdn t4i H. Chc di€m A,B di dQng tr€n d tho6 mdn tan giitc AOB vu6ng tqi O. Qua l, B vE chc fi6p tuy6n AE, BF cin (O;R) (E, F ld c6c tiep di€m). . a. Chring rninh: ZOAE = ZBOF b. X6c dinh vi tri cria A, B 1;1n d sao cho diQn tich tri gi6c ABFE dat giit tri nh6 nhAt. Tim gi6trinh6 nhAt d6 theo R. Bii 5. Cho a,b,c ld crlc s6 thgc duong. Tirn gi6 tri l6n nh6t cria bi6u thric: J,b Ji JA T-T- a+b+2c b+c+2a c+a+2b -11ft- Thi sinh kh6ng dugc str dpng tdi liQu. Gituir th!kh6ng gi6i thich gi thOm. Hg vd t6n thi sinh 56 b6o danh . tri l6n nh6t cria bi6u thric: J,b Ji JA T-T- a+b+2c b+c+2a c+a+2b -1 1ft- Thi sinh kh6ng dugc str dpng tdi liQu. Gituir th!kh6ng gi 6i thich gi thOm. Hg vd t6n thi sinh 56 b6o danh. X6c dinh vi tri cria A, B 1;1n d sao cho diQn tich tri gi6c ABFE dat giit tri nh6 nhAt. Tim gi6trinh6 nhAt d6 theo R. Bii 5. Cho a,b,c ld crlc s6 thgc duong. Tirn gi6 tri l6n. so cn-or HA riNn ps cHiNu rHrlc Bdi 1. Rtit ggn: oe rHr KHAO sAT cHAr Lr-IONG HQC KY r, LOp 9 NAM HQC 2014 - 20rs M6n: TOAN (Thdi gian ldm bdi: 90 philt) a. P:2Jn -oJf 6 -D'