1. Ngy thi 15-10-2012 S GIO DC V O TO H NIK THI TUYN HC SINH GII THNH PHMn TON - Nm hc : 2012-2013( thi chnh thc)Thi gian lm bi: 180 pht, khng k thi gian pht 3008H v tn:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S bo danh: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CU 1 (2,0 im) . Cho hm s y = x4 2mx2 + 2m 3.Tm cc gic tr ca m hm s c ba cc tr,ng thi cc im cc tr ca th hm s to thnh mt tam gic c bn knh ng trn ngoi tipbng 1.CU II (5,0 im) 1) Gii phng trnh : 5x 1 + 3 9 x = 2x2 + 3x 1 x(y 3 + 2) = 62) Gii h phng trnh: (x, y R) x3 (3y 2) = 8CU III (5,0 im) . 1) Tm gi tr nh nht ca hm s: y = x2 + 3x + 9 + x2 3x + 9.4a 4b2) Cho hai s thc dng a,b tha mn a+b+ab = 3. Chng minh rng :++2ab 7 3ab4 b+1 a+1CU IV (5,0 im) .Cho hnh chp S.ABCD c y ABCD l hnh bnh hnh. Gi M, N l hai im ln lt trn cc on AB ADthng AB v AD (M, N khng trng A ) sao cho +2 = 4. AM AN1) Chng minh rng khi M, N thay i,ng thng M N lun i qua mt im c nh .2) Gi V v V ln lt l th tch ca cc khi chp S.ABCD v S.M BCDN . Chng minh rng :2V 3 .3V 4CU V (4,0 im) . U = 2 1cho dy s (Un) xc nh bi :2 (N 1, n N ) Un+1 = Un 2Un 11) Chng minh rng dy s (Un ) gim v b chn.2) Hy xc nh s hng tng qut ca dy s (Un )................HT..............Th sinh khng c s dng ti liu. Cn b coi thi khng c gii thch g thm.