Menu Close

let-f-z-cos-3z-z-2-calculate-Res-f-0-




Question Number 63084 by mathmax by abdo last updated on 28/Jun/19
let f(z) =((cos(3z))/z^2 )  calculate Res(f,0) .
letf(z)=cos(3z)z2calculateRes(f,0).
Commented by mathmax by abdo last updated on 01/Jul/19
0 is pole of f with ordr 2 ⇒Res(f,0) =lim_(z→0)    (1/((2−1)!)){z^2 f(z)}^((1))   =lim_(z→0)     {cos(3z)}^((1))  =lim_(z→0) {−3sin(3z)} =0 .
0ispoleoffwithordr2Res(f,0)=limz01(21)!{z2f(z)}(1)=limz0{cos(3z)}(1)=limz0{3sin(3z)}=0.

Leave a Reply

Your email address will not be published. Required fields are marked *