( Thi gian lm bi 90 pht ( không k thi gian giao đ) !" # ! $ "% & $ & &'()#*+ , & -, & #, , & & ,", , & ! ./+0/1 , & -&! # ","%,," ! 23#*+45 x x x x x x x x + − − − ÷ ÷ − + 6789:;#*+4 # '()#*+4 & 2374<2=>34?5%7@)AB0*7;42CDB0*7E+ FG?HA 2+7I+4?2DB06JK # L6JK4?2D#84A5!7 & 2374<2FMN4C=>,84O@)PB0*7;4<CDB0 *7E+FGOHP 2+7I*7DE+FGOH4< # 2+7I+4D<OB063 74<2966+4D<OB06FM !"#$%&' ( )$*# +,-. ! !"5!- & !- 5" & $ ! # ! $ "% & $ & 5 $ & x x + − &'()#*+! , & -, & 5 & &, , & & "&, , & 5& & &, & 5& & , & # , , & & ,", , & 5 , , & & , & , - ,-, 5, & & , & ! &! Q! ! &! ! &! +, ./+0/1 , & -&! 5 , & -! & 5 , ! ,-! #","%,," 5", %,", 5", %, 5",&! , ! &! &! &! &! ,- RS x x x x x + ≠ ⇔ ≠− − ≠ ⇔ ≠ ≠ # ( ) ( ) ( ) ( ) & & & & x x x x x x x x x x x x x x − + − + Α = ÷ ÷ ÷ ÷ − + + = − + = − Q! &! &! +,- " ?6FT S+4?2DA45A2CA?5AD UK,+4?2DB06#60 &! &! &! ?6#604?2D µ VH = o UK,+4?2DB06JK ?D57 4D5W7 P6JK4?2DB0%W5$W7 & &! &! C&! C&! C&! +,- ?6FT /01231/4-5671289: OPB0=>#6;74<2 5XOP42OPB0=>#6;7 4<2 O042 ⊥ 4< V 4<2FMN4 5XOP ⊥ 4< P3OD ⊥ 4<NP PD5PO 5X4<B0=>;3NYDO UK,DE+FGOH4< #/71231/;<12=72>?4@/A1/=/B P45P<ZPD5PO 5X4D<OB06#60 4< ⊥ OD+7[ 5X4D<OB063 :32>??C-D9EF12A=/A=72>?4@/A1/ G9H12 ?634D<OB06FM\5X4<5OD \5X4<542F6OD542#I&OP UK,74<2FM/N46+4D<OB06 FM &! &! &! &! &! &! C&! C&! 2 O < D 4 . ?6FT S+4?2DA45A2CA? 5 AD UK,+4?2DB06#60 &! &! &! ?6#604?2D µ VH = o UK,+4?2DB06JK ?D 5 7 4D 5 W7 P6JK4?2DB0%W 5 $W7 & &! &! C&! C&! C&! +,- ?6FT / 012 3 1/ 4 -5 6 712 89 : OPB0=>#6;74<2 5XOP42OPB0=>#6;7 4<2 O042 ⊥ 4< V 4<2FMN4 5XOP ⊥ 4< P3OD ⊥ 4<NP PD5PO 5X4<B0=>;3NYDO UK,DE+FGOH4< #/ 712 3 1/ ;< ;12 =72>?4@/A1/=/B P45P<ZPD 5 PO 5X4D<OB06#60 4< ⊥ OD+7[ 5X4D<OB063 :32>??C-D9EF12A=/A=72>?4@/A1/ G9H12 ?634D<OB06FM5X4< 5 OD 5X4< 5 42F6OD 5 42#I&OP UK,74<2FM/N46+4D<OB06 FM &! &! &! &! &! &! C&! C&! 2 O < D 4