!"# $%#& '()*+,%-- +.,',/01(23(,%45+6*(không kể thời gian phát đề -"78#9:;<=>,?2@ AB<>,?2@ !"#$ %&!'( !")("*"+!"",-+."/ AB<>,?2@0123'4+5'6 7' ' ' " " " 8 8 x x x x x x π π + − = + + ÷ ÷ AB<>,?2@09123'4+5'6 : 7 ; < x x x y y x y y y + − = + + + − = + + ABC<>,?2@=>'>"1?'- @ 7 7 ' ' " ' x x x x dx x π π + + + ∫ ABD<>,?2@5'")1ABCD")BCD5'-E'4"F'A0GHIJ'2K +-'4("#BCBDLM4("#HDICN+O'4AM-E'44)"BCD P'4'M-E'44)"HD>'(>"$")1AIHC ABE<>,?2@Q23'4RS=54+!'R'T"#%(-P"6 U 7 7 x y x y x y x y + + + − + ÷ + + . -"7F!<>,?2@%+GH,0+I+J>KLI1(22M**NO0'+/,5+P0N,Q0'<"+P0+ORI"+P0 @ -+SOI+KT0'*NU0++BV0% AB=/<>,?2@=+'4V1W'4/"4"")X'B;L+G'4?0LX'C -Y"2Z'4W'4∆67[=5GY""X'C%N+O'4C C") GY'4-\' AB4/<>,?2@=+'4$E'44'/]"V1W'4U6][2Z'4W'4∆6 − − = = x y z V"J-A6 ] 87][M^N123'4+5'V 1W'4_'4'4∆-E'44)"UN1`"V"J-A ABW/<>,?2@=5a1K1(H%(-Qb'"1P"]" z i − − = =c)^ 51P"]R"1J'"#]%O'47 -+SOI+KT0'*NU0+A0'I/O% AB=3<>,?2@=+'4V1W'4/"4"BC")X'BL7CLX'-Y" 2Z'4W'4 Q6[+G'4?0CNQ9'>"4"0BC%O'43'!Q9' >"^5GYX' AB43<>,?2@=+'4$E'44'/]"V1W'4 U6][_6][ dN123'4+5'"#2Z'4W'4Qe-B[L[L'O+'4V1W'4_F V1W'4UY4)"%O'47; [ ABW3<>,?2@''4-\'Q23'4R ;; n n n n n n C C C C − + + + + = M^5F'4"P 7 +'4$+('"#U ( ) n x x + + X* &"& AB Y ,?2 AB Z[ / !"#$6 Z[ =a1"!'6Df 0F'6 L x x y y →+∞ →−∞ = +∞ = −∞ [; g 8Lg[⇔ [ x y x y = ⇒ = = ⇒ = − [; C'4%N'\'6 [; gg88Lgg[⇔⇒[& !")(-'@L[ & ! [; 3 &!'( !")("*"+!"",-+."/ Z[ g 8 [; g[⇔ ⇔ 3 2 3 2 1 3 1 1 3 3 x m y m m m x m y m m m = + ⇒ = + − − = − → = + − + [; QB/QC/⇔ ⇔: :[⇔: : 7:[ [; ⇔h 2 [; AB 7' ' ' " " " 8 8 x x x x x x π π + − = + + ÷ ÷ Z[ &,-$9'6'i[ ⇔ " " ' " " " x x x x x π − = + + ⇔ ' " " " ' x x x x x + − = [; ⇔ " " " ' x x x x + − = ⇔'"' " "x x+ ⇔ ' " ' "x x x x− = + ⇔ ' " ' " x x x x − = + [; ⇔ ' ' x x π π − = + ÷ ÷ ⇔ x k x k π π π π = + = + [; A',-$9'2K"123'4+5'")'496 x k x k π π π π = + = ± + . [; AB 09123'4+5' : 7 ; < x x x y y x y y y + − = + + + − = + + Z[ ⇔ : : 7 ; < x x x y y a x y y y b − + − = + + = + + + Y'4%jN6 : :7 8 : ⇔ : 8 8 : [; ⇔ " klm =")6 mg n[∀⇒m '4%N'+\'fm\'."+\'f [; D)"⇔mm⇔⇔ y + [; =%2K"6 8 o 7 y y y y y + + = + + + ⇔ 7 ;[⇔ 7 <;[ ⇔ A-+ da9")'49Q-'T [; ABC p@ 7 7 ' ' " ' x x x xdx x π π + + + ∫ Z[ @ 7 7 ' x xdx π π ∫ 7 " ' xdx x π π + ∫ @ @ [; =>'@ 6&V - ⇒-g g' G'" @ [ ] 7 7 " "x x xdx π π π π − + ∫ [ ] 7 ' x π π π + π[π [; =>'@ 6&V'⇒Q"Q &q"a'6 7 π ⇒7L π ⇒ ⇒ @ 7 dt t ∫ = 7 t 7− [; da@π 7− ; π + − [; ABD 5'")1ABCD")BCD5' -E'4"F'A0GHIJ'2K +-'4("#BCBDM4( "#HDICN+O'4AM-E'44)" BCDP'4'M-E'44)"HD >'(>"$")1AIHC Z[ =")6∆DI∆DBH ⇒ · · MDA NCD= ⇒ · · · · [ o[DNH MDA DNC NCD+ = + = ⇒M⊥DH [; I 5a ⇒M 2 2 4 4 5 5 5 DC a a CN a = = ⇒AM :[ [ ; 7 ; ; ; a a a a − = = [; A IHC A BCD A DI A BIH 7 a ; a [; D)d AIHC 1 . . 3 NMBC S SH = 2 3 1 5 2 5 5 . . 3 2 5 3 a a a [; ABE ]%Q23'4RS =54+!'R'T"#6U 7 7 x y x y x y x y + + + − + ÷ + + Z[ =")6 [ x y xy + < ≤ ≤ 7 ; x x x x + + ≥ + ÷ L 7 ; y y y y + + ≥ + ÷ [; Ur 7 ; ; x y xy x y xy + + + ≥ + ÷ ÷ ÷ r 7 7 7 7 ; ; ; xy xy xy + − ≥ − = ÷ ÷ ÷ [; 7 7 7 7 7 x x x x = ≤ = + + + + + =23'4*")6 ⇒ 7 7 7 7 7 7 x x x y x y x y x y + ≤ + = − + ÷ + + + + + + S 7 7 7 8x y − + + S 7 ; ; − = [; daUr 7 ; ; − DT-ss+⇔ daH'U 7 ; ; − [; AB=/ =4"BC")X'B;L+G'4?0LX'C-Y"2Z'4 W'4∆67[=5GY""X'C%NC C") GY'4-\' Z[ 0GH+-'4(C")6 ( ) L7 AM AG= = − uuuur uuur L8⇔ ; 8 M M x y − = − + = ⇔HL [; C∈∆⇒C%L7%⇒ MB uuur %L% [; HC ⇔% % ⇔ t ; b N b L = = ⇒%⇒CL [; =c)")L7 [; AB4/ V1W'4U6][2Z'4W'4∆6 x y z − − = = V"J-A6 ] 87][M^N123'4+5'V 1W'4_'4'4∆-E'44)"UN1`"V"J-A Z[ U")d=U= P n uur LL∆")d=U a ∆ uur LL _tt∆-E'44)"U'\'_")d=U=6 Q P n n a ∆ = uur uur uur 8L8LLL⇒_6]D[ [; A")?@LL%'$>'f 7 + + + = [; _N1`"A⇔Q@L_f⇔ 7 D − − − + = + + ⇔ 8 : D D = = − [; da_6]8[_6]:[ [; ABW/ =5a1K1(H%(-Qb'"1P"]" z i − − = =c) ^51P"]R"1J'"#]%O'47 Z[ 0G]∈f1P"")(%(-Qb'H =")6 z i − − = ⇔uu ⇔ : daa1K1(H2Z'4+v'A6 : [; =")]")1J'7⇒7H]R'\' 7 : ⇒ 7⇔h⇔ D)]7]7 [; AB =3 4"BC")X'BL7CLX'-Y"Q6[ +G'4?0CNQ9'>"∆0BC%O'4Q^5GYX' Z[ =")-Y"Q⇒L 0+G'4?∆BC⇒ 8 L y y G − + + ÷ \D AB uuur L⇒BC6 7 x y− − = ⇒BC6[LBC \D 8 L G G y y x y d G AB − + + − + − + = = y \D L GAB y S AB d G AB= = uu⇔h p⇒<L p⇒;Lda<L;L \D AB 43 V1W'4U6][_6][ dN123'4+5'"#2Z'4W'4Qe-B[L[L'O+'4_F V1W'4UY4)"%O'47; [ Z[ =")6 ' LL = r Yj"311-N'"#_ % L L = − r Yj"311-N'"#V1W'4U 0G L%L" = r % " n[Yj"3"X123'4"#Q d52Z'4W'4Qe-B[L[LB ∈ _Q) Q"P+'4_ ' ⇔ ⊥ r r ' [ % " [ ⇔ = ⇔ + + = r r ⇔"% [; 0)"K1%wQU%O'47; [ [ % ' 7; "% % ⇔ = = r r r r r r [; ⇔ % " : % " 7 % " % " − + = ⇔ + + = − + + + ⇔ox % % yx%%y ⇔o; ;% :%8% o% ⇔; ;% :% 7%7% ⇔ % [⇔h% [; %6G'%⇒"7 %6G'%⇒"[ daQ6 7 x t y t z t = = = − Q6 x t y t z = = − = ""2Z'4W'4"J'5 [; AB W3 ''4-\'Q23'4R ;; n n n n n n C C C C − + + + + = M^5F'4"P 7 +'4$+('"#U ( ) n x x + + Z[ =") [ n n n n n n n n n C C C C C − + + + + + = + = ⇒ n n n n n C C C + + + = − =j4N") ' ;; ⇔ ' ;8 : ⇔ ': \D U : ( ) : : [ k k k C x x = + ∑ = : : [ [ k k m k m m k k m C C x x − = = ÷ ∑ ∑ : : [ [ k k m k m k m k k m C C x − − = = ∑ ∑ \D zC= ⇔ 7 [ : k m m k m k Z − = ≤ ≤ ≤ ∈ ⇔ [ < : m m k k = = ∨ = = \D daF'4"P 7 6 < [ < : 8 : < : : C C C C + 7 \D . $%#& '()*+,%-- +.,',/01(23(,%45+6*(không kể thời gian phát đề -"78#9:;<=>,?2@ AB<>,?2@