: Lrru Nhu Hda, 12 To6n, THPT Hoang Vdn Thu h;
CUOC THI OLYMPIC KHOA HOC
(Tiep rrang 23)
Vi6t Nam thuOc vho top 10 trong 30 dodn du
thi. Kdt quA niy lh cao hcrn so vdi du kidn.
Dd thi cho thAy cdc nudc day nhidu vdn dd
hon vd hoc sinh chting ta cfing hing tring nhi6u
trong bdi tric nghiOm chung. Nhu vAy, chua c6
co s6 dd n6i hoc sinh chring ta hoc qu6 tii.
Hudng tidp cAn vdi thd gidi vd m6n Khoa hoc
c6 16 nOn theo hudng day r6ng ci{c vdn dd v}r
tfch h-o. p chrl khOng chia c6t thinh nhidu mOn
v6i kidn thrlc sdu o cdp THCS.
Tru6c ki thi ndy, d6i tuydn cta chring ta chi
cluoc luyen 5 budi. Nhu vAy kdt quA trOn phAn
6nh chat luong clay vir hoc Khoa hoc c[ra chfng ta, chrlt khOng phai ket qud clra "gh ndi". N{Ot
dieu d6ng milng la tiing Anh cita hoc sinh ViOt
Nam du thi lh khr{ tdt.
Ban tti chrlc cfrng dd quydt dinh hidn chucrng,
di6u l0 cu6c thi vi danh s6ch c6c nudc dang cai
ddn nim 2009. Ricng nlm 2005 c6 thd lai thi
ti6p tai Ind6n0sia do chua c6 nu6c nho nhAn
dang cai. Duoc bidt chi phi td chrlc cu6c thi
nam nay th hon 1 triOu USD.
Prove that the sequence (xr, ) has a tends to infinity and the limit is an irrational.
T10/331. Find all positive integers n > 3 so that the
following inequality occurs for n arbitrary real numbers a1, at, ..,, a,, (a,,*, = ar) '.
I (ai -a
l<icj<r
T11/331. Determine the form of triangle knowing that its angles satisfy the condition
ts@ l2) 1 + tg(B lz)teC l2) tec l2) ts(B I 2) t+tg(C l2)teAl2) I t+te$l2)te{,B 12) 4tei/,1Z)te(.B lz)ts(c l2) Tl2l33l. Consider the rectangular parallelepipeds
ABCDATBPP, such that the lengths of the side,4-B = a, AD =' b, AA, = c and the distance between the lines
AC and BC, are natural numbers. Find the least value of
the volumes of these parallelepipeds.
30
-
3.(A\\