Gửi Tiến Thành bài ĐXC

   !" #$%& ' (%)& ' *+,!(% /01*+2%3 4!"#&56& ' 7*+$%  0)8 ! 0/  09: " 0;6 <=> ? ' ' ? ' ' ? ? ' ' '' ''   '  ? '  ' ? ' ?           @ )@ & & @ & )& @ ) A A @ @ @ @ B@ @ C @ @ @ ) )@ ) @ @ =  =   =>   =  =   = => = => − = − − => − =− = => D7A ' 5A ? 50/A   EF '' ' ' ? ? ? ? ? ?    ? '  G  G 0/ 0? 0/B@ @ C  )B@ C @ )  @= => = − => = − ' '    @ : ? @ 6  =     = =  >  6 ' ' 6 6 6   6 ' 6 ? ?  ? ?    @ 6@   & 6&  @  ?  B  ? 09:6 ? @ @ C  B C @ 9 ? 9 6   = =   = => => ϕ = = =   + − + − = =  