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Question Number 74914 by arkanmath7@gmail.com last updated on 03/Dec/19
Can someone solve this question plz?  solve the contour integral   ∫_C  (e^(iz) /z^3 ) dz where C is the circle ∣z∣=2
Cansomeonesolvethisquestionplz?solvethecontourintegralCeizz3dzwhereCisthecirclez∣=2
Answered by mind is power last updated on 05/Dec/19
pols of f(z)=(e^(iz) /z^3 )  has pol at z=0 order 3  ∫(e^(iz) /z^3 )dz=2iπ Res(f,0)=2iπ.(1/(2!))(d^2 /dz^2 ).z^3 f(z)∣_(z=0)   =(1/2)2iπ(−e^(iz) )∣_(z=0) =−iπ
polsoff(z)=eizz3haspolatz=0order3eizz3dz=2iπRes(f,0)=2iπ.12!d2dz2.z3f(z)z=0=122iπ(eiz)z=0=iπ
Commented by arkanmath7@gmail.com last updated on 04/Dec/19
this qust. isn′t solved from Schoum′s and the  answer is −πi
thisqust.isntsolvedfromSchoumsandtheanswerisπi
Commented by mind is power last updated on 05/Dec/19
yeah Res(f,0)=(1/(2!))(d^2 /dz^2 )z^3 f(z)∣_(z=0)
yeahRes(f,0)=12!d2dz2z3f(z)z=0
Commented by arkanmath7@gmail.com last updated on 05/Dec/19
thank you sir
thankyousir
Commented by mind is power last updated on 05/Dec/19
y′re welcom  we can generaliz it  ∫_C (e^(iz) /z^n )dz=((2iπ)/((n−1)!)).(i)^(n−1)     =((2π.(i)^n )/((n−1)!))
yrewelcomwecangeneralizitCeizzndz=2iπ(n1)!.(i)n1=2π.(i)n(n1)!
Commented by arkanmath7@gmail.com last updated on 06/Dec/19
good work thanks again
goodworkthanksagain

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