a Chring minh fra gi6c BCKF li'hinh thang c6n.. tri iliom E sao cho do4n thdng KD c6do dai nho nhat.[r]
(1)a UBND HUYPN QUANG TRACH PHONG CrnO DUC - DAO TAO DE THr CHQNHQC SrNH GrOr LOP VONG I ttAtvt HQC 2013 - 2014 MOn tlti: To6n Thd'i gian:150 philt ( Kh6ng k€ thdt gian giao di) S5 nao danh: Ciu I: (2,0 di€m) Phdn tich cdc da thric sau thdnh nh6n ru a) 2x2 + xy -3y' - 6*y b) (*' *10x)(x'z + 10x +z+)+ 128 Cdu2: (2,0 diArn) a.) Gi6i phuong trinh #.*,*ir b) Tim sd nguy6n duong x th6a m6n ].1= 2ol4t' !(,.+)f,.1)[,.+) 2[ r.3/(- 2.4)\' 3.s) [f,.-,,(**2)))2013 L(.^ Jur2 Cflu 3: (3,5 di€m) Cho tam gi6c ctAu ABC,E ld mSt dii5m thuQc cqnh trung di6m cria doan thdng AE Eudng th5ng di qua AC vitkh6ng trung v6i A, K lit E vitvu6ng g6c v6i cludmg thtng AB tai F cltducrng me"g di qua C vi vu6ng g6c v6i clunng th[rg BC t?tdi6m D a) Chring minh fra gi6c BCKF li'hinh thang c6n b) Chrmg minh KE.EC: ED.EF tri iliom E cho do4n thdng KD c6do dai nho nhat cia 4: (1,5 di€m) Tim tet ce c6c st5 nguyCn tti p co dang: p : r{ * 1, n lit c) X6c dinh vi mQt sti nguycn ducrng, bitlt ringp c6 kh6ng nhi6u hcrn 19 chfi s6 Cf,u 5: (1,0 di€m) Cho c6c s5 a, b, c ducrng th6a m5n a * b * c a - b ' -,32' l+b2 l+c2 ' l+az -H5t Ghi chri: Cdn b9 coi thi kh6ng gidi thich gi th1m./ =3 Chrmg minh rang ' a a (2)