: hm(f (x'y+x) f (x' il)= f(x)-f (o)
ndr o6xc afiN r$n Tdng bian fip : TS PHAM THI BACH NGOC
IHIU rnAcu Nururu xuAr aAtt
Chri tich H6i tldng Thanh vi€n ki6m Tdng Gi6m d6c N)G Gi6o. duc Viet Nam
NGUT.NC,OTnANaI eh6 Tdng Gi6m ddc ki6m Tdng bi6n tap NS Gir4o duc Vi6t Nam
rs. NcuvEN Qrri rsno
Thu kiTda soan : ThS.ffd QUINC vfNg
rs. rnAN oNH cHAu, rm. NcwEN ANH DLTNG, rs. rniN NeNt ofNc, rs. NGuYEN MINH Dttr, rs. NcwiN
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il -6* ;inr nai pGS. rs. r.E quoc nAN, rus. rHAM vAN HLING, pcs. rs. vir rn,cNH rHdr. GS. TSKH. NcuyBN ,rA* n hu, 6ng NGUyf,N rnAc unoH, zs. rn-iN uftu Nev, PGs rs. NcuveN oANc puAr, pcs. rs. TA Dt-ry pHrxllrc, ms. NcureN rrd rnAcu, GS.TSKH. oANc silNc rnENc, PGs. rs. PHAN DOAN THOAI rrs. vU rIu rsuv, pcs. rs. vU luoNc rHUY, GS.TSKH. NcO vIEr TRUNG.
SOh6 h6
phrtong phuong
Problems
Giii c6c bdi cria sO'+Og.
@ ,Ot thio khoa hgc c6c chuy6n dd to6n
hoc vd ddo tao, b6i drrdng gi6o vi6n trung
hoc cd s6 t{ Vtnh Phtic.
@ XCt qui cu6c thi giii To6n vi VAt Ii tr6n Tap chi Toin hoc vd Tudi tr6 n[m hoc 2010 - 2011.
O Thrl srlc trudc ki thi - oa'saz.
Ban doc tim tdi - Reader's Contributions
Huj,nh Tdn Chd,u, Nguy6n Diruh Thi ' Srt dung nguy6n 1i Dirichlet trong chiing minh bdt d&ng thilc.
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BiAn tdp: NGLIYEN THI THANH
i:ri ,i,'ori, hdnh :NGUYEN KHoA DGM, vtl ANH rHu
Bia 1. Trudng DHKHTN, DHQG Hn NQi. Bia 2.Thdy tOi - Gi6o su Hoing TqY.
Mi thwit; MINH THO
ChA,bdn; NCTTT4N THI OANH
TRONG SO NAY
Dinh cho Trung hoc Co sd - For Lower
Secondary School
Nguydn Khd.nh Nguy€n - Srl dung tinh chat d6'i xung dd giii m6t sd bdi to6n
hinh hoc.
@ Nfrin ra th6 gi6i - Around the World Nsuydn. Hdi Ch6.u - Gi6i thi6u mQt sdbii
todn cia chtlong trinh d6nh gi6 hoc sinh Qudc td (PISA).
O D6'thi vdo I6p 10 Tnrdng THPT chuyon @ UO ra ki niry - Problems in This Issue Lam Son, Thanh H6a nim hoc 2011 - 2012, T 1l 473 .... Tl2l 413, Lll 473, Lzl 4L3.
O SL:iL"Xi"ti,J,1: uut hqc - universitv