3R
Dien tich A M P Q dat gia trj Idn nhat o x = — . Chung ta "chinh he s o " va roi van dung bát d i n g thtfc Co-si cho hai so di/dng, nhir vay da c6 diTcJc Icfi giai cua bai toan.
Cty TNHH MTV DWH Khang Vỉt
D E S O 3 4
DE THI TUYEN SINH VAO L(3P 10 THPT, TJNH BAC LIEU NAM HQC 2010 - 2011 , , NAM HQC 2010 - 2011 , ,
pai 1 : (2 diem) ThiTc hien phep tinh :
3) iVsO + V 2 0 - >/45 + 5 b) ^ ^ ^ + ' ' " ^
jjai 2: (2 diem) Cho he phifdng irinh mx - y = 5 (I)
X + y = 1 _ .1 nv^iu%a (»' o • ,
a) Giai he phiTctng trinh (I) vdi m = 5.
b) Vcii gia tri nao cua m thi he phiTdng tnnh (I) c6 nghiem duy nhat, v6 nghiem ?
Bai 3: (3 diem) Cho phÚdng irinh : x^ + (4m + I)x + 2(m - 4) = 0, vcfi m la lham sọ a) Giai phúdng trinh vdi m = 1.
b) ChiJng minh rang phiTdng trinh luon c6 hai nghiem phan biet v d i m o i m. c) T i m m de phúdng trinh c6 cac nghiem X|, X2 thoa man : (X| - Xj)^ = 65. c) T i m m de phúdng trinh c6 cac nghiem X|, X2 thoa man : (X| - Xj)^ = 65.
Bai 4: (3 diem) Cho mot diem M bat k i nam tren nuTa diTdng tron tam O dúdng
kinh A B ( M khac A va B). Tren nvia mat phang bd A B chiJa nufa dúdng tron,
ke tiep tia B M tai F ; tia BE cat Ax tai H va cat A M tai K . a) Chiirng minh E F M K la tiJ giac noi tiep.
b) Chu-ng minh : A l ' = I M . I B . c) ChiJug minh tam giac B A F can. c) ChiJug minh tam giac B A F can.
HV6NG D A N G I A I B a i l : B a i l : a) - V 8 0 + V 2 0 - N/45 + 5 = - V l 6 ^ + V 4 ^ - V 9 ^ + 5 , 4 4 = -.4N/5 + 2 V 5 -3N/5 + 5 = 7 5 + 2 V 5 - 3 V 5 + 5 = 5 4 b) X - Vx ^ X - 1 _ N/X(VX - 1) ^isfx + I)(N/X - 1 ) Vx N/X - 1 \/x Vx - 1 = Vx - 1+'Vx + 1 =2%/x ( x > 0 , x ^ 1 ) ^) V d i m = 5, (I) trd thanh: fx = l J x ^ l 1 + y = 1 <=> y = 0 X = 1 1 + y = 1