PHoNG GrAo DUC vA DAo rAo orpN euAu on rnr cHeN Der rwfN D[/ THr Hec srNH crOr riNn NAM HQC 2013-2014 M6n To6n - (Thdi gian ldm bdi 150 philt) Bni 1.(5 tli6m) ) ); ) 2. Tim nghiQm nguy€n tti cria phuong trinh: x'-2y' :1 Bni 2. (s dicm) 1. Cho x > 0. Tim gi6 tri cria x eC UiCu thfc: M: ; l-, dat gi|tri lcnr (x +2013)" nh6t. @' 2.Cho a + b * c:0. Chrmg minh ratrg' ao +bo *c4 :I@ *n, +c2). Bni 3. (s dicm) it l. Cho 3 s5 a,b,c th6a mdn tli0u kiQn: 01a,b,c <t . v/ Chrmg minh r6ng: a, +b2 *c2 <l+azb*b2.c+c2a. 2.Basti thgc a,b,c th6a mdn hQ thfc: b+c < 0(1) bc* ca> 0(2) . Chrmg minh a,b,c ( 0. < 0(3) Bni 4. (s dicm) l. Cho tf.gi6c ABCD c6 AC "at gO tpi O. Ggi diQn tich cria cilc tarn gi6c AOB, COD lan luqt bdng S, vd S, , diQn tfch cria bl gi6c ABCD bdng S. Aaa.rJ',t, Uhrmg mrnh rdng: V^S > ./S, +./E . ! 2. Cho ttuorJg trdn tdm O nOi ti6p trong mQt tam gi6c ABC vd ti6p xric v6i c6c cAnh AC, BC 16n lugt tai M vd N. C6c ducrng phan gi6c cta c6c g6c A, B ctra tam gi6c ABC cit dulng thdng MN lAn lugt tpi P vd Q. Chrmg minh: MP.OA: BC.OQ. HCt . l-, dat gi|tri lcnr (x +20 13) " nh6t. @' 2.Cho a + b * c:0. Chrmg minh ratrg' ao +bo *c4 :I@ *n, +c2). Bni 3. (s dicm) it l. Cho 3 s5 a,b,c th6a mdn tli0u kiQn:. PHoNG GrAo DUC vA DAo rAo orpN euAu on rnr cHeN Der rwfN D[/ THr Hec srNH crOr riNn NAM HQC 20 13- 2014 M6n To6n - (Thdi gian ldm bdi 150 philt) Bni 1.(5 tli6m) ) ); ) 2. Tim nghiQm nguy€n. thgc a,b,c th6a mdn hQ thfc: b+c < 0(1) bc* ca> 0(2) . Chrmg minh a,b,c ( 0. < 0 (3) Bni 4. (s dicm) l. Cho tf.gi6c ABCD c6 AC "at gO tpi O. Ggi diQn tich cria cilc