: (BT, BX ) (CY, CX) (mod zr)
gi6ng dpy Toirn cd nu6c trinh biy k6t qu
nghi6n. ciru cria minh trong vong .5 narn gAn
tl6y. D6ng thoi trao d6i, th6o lu4n v.e nhirng vdn
dC thdi sg cAp thi6t trong ph6t tri6n To6n hoc
cta ddt nu6c. Tham d1r Dpi hdi c6 hcrn 700 dai
bi€u <v c6c Vp, c5c Vi6n, c6c Truong Eai hgc,
Cao ddng trong nuoc vd Qu6c t6, c6c Trudng
THPT, Nhd XuAt bin Gi6o dUc Viqt Nam. C6
357 b6o c5o dugc trinh bdy tai H6i nghi trong
t16 c6 5 b6o c6o moi (o 5 phi6n todn th6) vd 43
b6o cilo m<ri t4i 8 ti6u ban.
Trong dip ndy, HQi Torln hgc Vi6t Nam cl6 tidn
hdnh Dqi h6i dai bi6u nhim ctSnh gi6, t6ng k6t nhtng thdnh tuu ph6t tri6n to6n hoc
trong 5 ndm qua, ghi nh6n ket qqa hopt dQng
cira Vi6n Nghi6n cuu Cao cAp vO To6n cl6ng
thoi neu ra dd cuong ph6t tri6n trong 5 n6m t6i
vir b6u ra Ban chAp henh HQi To6n hoc ViQt
Nam nhi6m ki 2013 - 2017 gdm 19 thdnh vidn (enh dudi). GS. TS Nguydn Hiru Du (Truo-ng
DHKHTN, DHQG Hd NQi) clugc bdu lA Chu
tich, GS. TSKH Phlng na.nai (ViQn To5n hqc
ViQt Nam) clugc bdu ld Tdng thu ki ki6m Ph6 Chn tich H0i.
Tqp chi Todn h7c vd Tudi te xin chric mimg thdnh c6ng cira Dpi hdi To6n hgc ViQt Nam 16n
thf VIII.
PV
ll l j .,.. ur--s ,J c6s li + r:iis lj ctlr ('." cor ('c,.r.s ..,i
--f *os .I cus il,u, {' < 1.
)-
N6u ta thay tl6i gi6 thi6t a2 + b2 + c2 + abc:4 cria bdi to6n g6c thinh ab + bc + ce + abc :4
*(,t*)' .('t*)' .(J-A)' +'[oo.n!o, J*=q
thi chirng ta s6ng t4o ra mQt sd bdi to6n sau.
{"} ffiii !**cl ?, L'!ttt i'ti. ',iLiirlrrl{ ^-int tt. I't. t llti:r nritti ub I l;t' l-t'r;+.uht'.=:tr . t'hil'u,g rttitth ctic
htit liing !itt'i'L' .\'t:ur i ) s1.,,' :' i ; - l-7 I; -r ) i ,//r, .( r r, -- vl - .-. ) .. .i, -i) rrl i /rr'rirrr23 i rci '.1, .,,1 'i trltt > 3'Jafu ; t'((t ''i ( ' .,/ ,, tl t, -;:-
til ,,/ir\/\ \(i1:', --'.,1,''-1)- ,. lrt ,,.]-r irl I
t- ; r ,- 2
,) ilt- t1r* ",/r - \( -1rt/)i'1 r: .
tl ttht
Ta tdng qu6t bdi to6n ban clAu nhu sau:
Cho cac ti5 kh6rg dm a, b, c. Tim sd k kharg
,:
am lon nhat thoo mdn cac didu ki€n
a2 + b2 + c2 + kabc =3+ k vd a+b + c <3.
Circban hiy thu ldm nh6!
TOftF{ HQE