. Nghiem cua he phiTdng trinh la (1; 0)
a)ChiJng minh phúdng trinh c6 hai nghiem phanbiet vdi mpi gid tri cija m b) Gpi Xi, X2 la nghiem cua phúdng trinh.
b) Gpi Xi, X2 la nghiem cua phúdng trinh.
Tim cac gia tri cua m sao cho x f + X j + 3X|X2 = 14.
Bai 3: (1,5 diem) M o t ca-no chay v d i van toe khong doi tren mot khuc song dai 30 k m , ca d i va ve het 4 gid. Tinh van toe cua ca-no khi nifdc yen iSng, biet
van toe cua dong nifdc \h 4 km/h.
Bai 4: (3,5 diem) Cho tam gidc A B C vuong tai A (AB < A C ) . Tren canh A C lay
diem M (khac A va C). Difdng tron difdng kinh M C cit B C tai E va c^t
difdng thang B M tai D (E khac C ; D khac M ) . a) ChiJng minh tiir giac A B C D npi tiep.
Chifng minh A B D = M E D . -^f^ •
c) Difdng thdng A D cit difdng trdn difdng kinh M C tai N ( N khac D). Difdng th^ng M D cit C N tai K, M N c^t CD tai H. ChUng minh K H song song vdi NẸ th^ng M D cit C N tai K, M N c^t CD tai H. ChUng minh K H song song vdi NẸ
^ a i 5 : (0,5 diem) T i m gia tri nho nhát cua y = ^ + 3%/^+1 > i ) X + 4Vx - 1 + 2
H I/ ( 5N G D A N G I A I
L u y § n gi^i iS6 truflc k1 thi vao lap 10 ba mjgn B^c, Trung, •guySn Ddc T9'n
c - 5 PhiTdng trinh c6 hai nghiem phan biet: x, = 1 ; X2 = - = — PhiTdng trinh c6 hai nghiem phan biet: x, = 1 ; X2 = - = —
a z b) 2x - y = 3 3x + y = 7 <=> 5x = 10 X = 2 3x + y = 7 [6 + y = 7 X = 2 y = r
Nghiem cua he phifdng Irinh la (x ; y) = (2 ; 1)
c) M = i V 3 2- 2 V ^ - H : # = i V^ - 2 V ? : ^ + ^
2 vri 2 Vn
= 2%^-10>/2 + >/2 = - 7 ^ • N h a n x e t : ' * ' A ^ , a) Nhan r a a + b + c = 2 + 3 + (-5) = 0