!"#$""#$% &'!() *+,$ !"#$ %##&$'&()%*+,- .+&"/0"12 &()%3 4566#&789:+7-:-./-$*- 0;<*$ !="02$'$>?@3;A#&+B C+B#D0E;F1;G>3 *+,"% $ &!:H++B9IJ % 08 K$>H*!?(LM-*"(*$>!+-*0N+B0 OPD0,*#QL-*!?(KL*-+R"R S0 13TO UM = 3 0V+(W!+"R 3X+$"#D0$>?Y.+"Z3 [W!+"R 3[$>"(+BV$ M M \ = 1 .+"("R 31&!0W0$ R 3 *+,%]&70O*#H6^ -^ +R+7"60_M3 `>PV+R$,$"6#P$ O*#^ *%ab3c !de&S0O*#^ $ O*#^ *%bb3f+R O*#H^$ "*%W00O*#^ $ ^ +7"61>O ,0$"#K$ fD0O*#^H0#O08 g[O*#^eK1%/0&*0+=$ ^ KL4h3 g[O*#^ef1%/0&,+;,+*+=$J$"#D0$> PV"O*#^ 3Vf? 9O3#)D0O*#$ +^ f3 *+,- K$>)&+7Z090++'F0d;A,;A"18 π = $ 4b- ϕπ += 3iA"190+=(;+( ? 8 b- ϕπ += 3V ϕϕ < $ P +"?O3X+P 0C- j $ j3 K?.?FC"<k+213`>,*!?(L*-?FCl ,+2*LMMfU3mRVS0+n$>+B?FC,'9 )3] VB+C!09+'*$>!+$0!0LU 3TO UM = 3 0#Z0N*V.+B++*$>"ZV3 o0*"ZV1$>90++'F03`;A"190+D0$>3 ]J"6J0+k+2-'9AC!-!J0+$"#:SD0$> -!Z0? ?Y$>+/0$"#?FC_$'$"#:S3 X+Z+B$>+/0$"#,+EO;4?E?2M43 pppppppppppppppqrpppppppppppppppp Q ^ q1 P V V * q1 "#$""#$% &'!() *+,./ 0102 /3 *+,$ h+B $4*0 567 ,8259:;<2=>?/0;02@ pT(,06*2$ *sE3 p]0 J W+A$*2A+!+?>;3 pq++J>;D0J#(;$&..N+A $*2-Y@6D0N+*B%+1!-D ! -"0 $' 3 p1W12J>;;d(;$t+A$*21:- +,-? #&3333 pq++t"eD0$A2$t+D0J -9)*1!;,BC"03 p5)*Z0t+3 pX++'*&J8+79d#&-t "e333 "4ABC>D2?/E! + Hin tưng t cm khi đng mch. !"# !$%&' m,[1+um ?0F+u m ?NNR9d+&"ee 0!03 !()* [+,[9F+&"%0 ENM+v3f" 9F+&E? N/0!9:0+= ⇒ "!9:CO&9F+&%23<+?>T<pCA9F+& %2,96!?:"0,9F+&" *E?0,3`1$>m ?NN3 + Hin tưng t cm khi ngt mch. !+"# !$%&' [.[,+um*.0 ?,<"70+,.3 !()* [.[9F+&" Nv+M? N/0!9:0+= ⇒ "!9:CO&9F+&%23 <+?:T<pCA9F+&%2d'$9F+&"9 7:"0-9F+& +/0+um3KR*"Z0.[1Z 0C"0)N"OHZ+9F+&%2"0"O ?9+,? +um?,<?"7.3 %4;>3>D FG 21H2?I wT8TO(9:+7,'9 ? S'9 D0E;F3 pK.A9:+7$ +&1$x pN#&0C++(v$ yD09:3 pm&"eD0+9:8 , - . = 3 pKR*0,8 , -+ / , - + / . ρ ρ =⇒== p5d:C+*!?(D0+9:? 8 0/ ++0/ =⇒= Q m T-Q [ z-" " m [ m z-" T-Q V A pN$ 0,8 0, - / ρ = p5d%"0$>?@"0+(+&"eO{$ *!?("5D0+7N+, 1+('9 D0E;F? ? wT8TO(9:+7,'9 ? S'"D0E;F$ ? ?01+(? 3 wT48TO(9:+7,'9 ? 4 S'0D0E;F$ ? ?01+(? 4 3 p`>B#D0E;F+(C+8`L? 3? 3? 4 *+," b+B G4J02 K,B6L ?/M NB92>OP2Q>:R2I p]J!ER 3 piA"1B+D0$> "R8 12 =+ p|%G]$>.+"Z3 p]?]^0,8 . 3 12 4 =− α ⇒ . 3 1 4 −= α p`>"Z*fLM ⇔ M =− . 3 4 α ⇒ α .3 4 = 4 p};96+?>% AE-0,8 ]P ~~ = ⇔ α .3. 4 += ⇒ α −= .3 4 a N4$ a ⇒ 4 = α b p`>$>"Z+0 ] $R ? 8 4 h_-M 4 ≈== α h 54ST2??/M502 K, NB92>OP2Q>:R2I p]J!ER 3 pX•$>$"#|"PV *0"(" $ β =( \ 3 piA"1B+D0$> "R8 12 =+ p]?|^0,8 . 3 12 ( =− β ⇒ . 3 1 ( −= β _ pKR*;96+?>% AE-0,8 |P ~~ = ⇔ β .3. ( += ⇒ β −= .3 ( € pN_$ €0,8 4 −= β 1 • piA"1+?)JD0K*+28 M =+++ 1562 p];A"1?&C^8 +=+= == ββ ββ 17176 115 M p[.+"(18 M M== θβ $ ‚ Lƒ„ pNM$ 0,8 θθµ 117 =+ Mb-M 4 4 ≈ −+ − = + =⇒ θθ θθ θ θ µ 7 17 1 UE>N2? +,./B92672?! α P ] ^ 2 1 Q ^ θ 2 P V 6 1 1 2 C 5 *+,% a+B V0 B92>/P, W FG 0 >X,YD2I poA+7%8 w[0,[^8 U U 8888 →→ w[,[^8 U 44 UU 44 U U 888 888 →→→ gq8[^eK3 p5%!d*+=[^*,963 M UU U ==⇒≡≡⇒ 88 3 p0,8 4h U U 878788 =−=⇒==+ M U U 88 88 9 = + =⇒ 3 p0,8 4a4a 44 U 888 =⇒==+ 4M U 44 U 44 88 88 9 = + =⇒ gq8[^ef3 pmB+;,+%/0&*+=OO;$"#D0PV10& $"6#0?,"0*H&$"6#3 p0&$"6#$>PVe$d3 M U 988 ==⇒∞=⇒ 3 M U U U 1 8 8888 ==−=−=−=⇒=+ p0?,"0*H&$"6#3 4M 4 U 4 988 ==⇒∞=⇒ 3 8 8 88 −=−−=−−=⇒−==+ aM4M_M 4 U U 4 pX•[^0,8 wMM€MMhM aM M U 9 8 89 =++−⇒ − + − =+= 99 MMMM€MM•MM U −=+−=∆ 3 p5f? 9Ow,& bMMMMM U 99 =⇒=−⇒=∆⇒ p`>8CL^ fL4M *+,- h+B $4V0 B92 $ZG[4\ ] " ^R] pN+7$•pA0,8 3 ϕπ α ϕπα − =⇒ − = p58P$ ϕπ − *+= +BP 0C *…L π α =⇒ 3 pTY+,0,8 b 0C =+= p`>8 h b h 0C π ϕ π ϕπϕπ =⇒=−⇒==− pi00+D090+=(;8jLj †…L‡U4 "4JR/>;02 ;2_` _H[;I G4a>b/?/G2>c_d ,e32B=2?Bf2_d ^g>Ob/?/0JI piA"1+?)JD0$>8 9 igfg‚ L0 r r r r 3 p]?^C8pfp* /∆ L0 ⇒ fL†0p* /∆ p[$>"Z1fLM M€-M / = − =⇒= − =∆⇒ 54/f>16A2?>Oa2hG;B=2?I piA"190+8 ϕϖ += * 2 1 5 8 V ^ C j j … ^ C p!,8 UM :8 == ϖ p[$>e`]V8 ⇒=∆−⇒=+ MM MM /52 / M-M M ===∆ 3 p„+Z$>++(+*"ZV? 8 0 oL LM-M€ L€3 pT+D0$>*"ZV? 8CL€pMLp3 p`>!D0$>*"ZV? 8$L0L aM U3 pV+90+D0$>8 3 h =+= ϖ 3 p[LM 4 M U M 4M_ M MM π ϕ ϕ ϕ −=⇒ < −= ⇒ > −=−=∆−∆= ⇒ 3 // 3 piA"190+8 4 Mh π −= 3 4b/B/3^g>i,G^9>OD jk B l%k > _K2"#$%! p[ 4 a4 ;;;; ±=±=⇒ =⇒= p[LM > −= ⇒ M 4 M M 3 ⇒ ˆ$+BK M "$F"F3 p[$>/0$"#,~ + L4~ ?+2$+BK "$F"F3 p|,/•2$Z+B$>/0$"# ,~ + L4~ ?2M4? 8 παϕϕ +−=∆ p` bM4 a M4 ‰ 4 = − ==⇒== π αα p`>8 4M 4M• 4 4M• 3bM4 44 π ϖ ϕπ π ππ ϕ = ∆ =⇒=+−=∆ Ch : 4<=>?)@<<3ABC P pP K K M LK a pPU PU K 4 Š K . −= β 1 • piA" ;1 +?)JD0K*+28 M =+++ 15 62 p];A" ;1 ?&C^8 +=+= == ββ ββ 17 17 6 11 5 M p[.+"( 18 M M== θβ $. =+ Mb-M 4 4 ≈ −+ − = + =⇒ θθ θθ θ θ µ 7 17 1 UE>N2? +,./B92672?! α P ] ^ 2 1 Q ^ θ 2 P V 6 1 1 2 C 5 *+,% a+B V0 B92>/P, W. W+A$*2A+!+?>;3 pq++J>;D0J#(;$&..N+A $*2-Y@6D0N+*B%+ 1 !-D ! -"0 $' 3 p 1 W 1 2J>;;d(;$t+A$*2 1 :- +,-? #&3333 pq++t"eD0$A2$t+D0J -9)* 1 !;,BC"03 p5)*Z0t+3 pX++'*&J8+79d#&-t "e333 "4ABC>D2?/E! +