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Sorry to bother, but this is the last past paper I'm solving before the exam and I just can't get it right at all >.<
Darn complex numbers!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_33.pdf
It's question ten, usually i try as much as I can from complex number questions and let it be, but since this has eleven marks I'm really scared
Also, the document Akira shared didn't quite help me understand the solution, sorry..
Anyone?
Esme
littlecloud11
10i) u-w =4i ----1 and uw = 5--------2
u= 5/w
substitute this in eq 1
5/w -w =4i
5-w^2 = 4i
w^2 +4i -5 =0
w= -4i +/- √{(4i)^2 - 4*-5*1}
w= -41 +/- √(-16+ 20)
w = -4i +2/2 -4i-2/2
w= -2i+1 and -2i-1
u= 5/w
u= 5/1-2i
u= 5(1+2i) /4+1
u= 10i +5/5
u= 2i + 1
and it's conjugate u= 2i-1
ii) Sorry this is a little messy-
The red shaded region is the answer for part ii
iii) I labeled the length of the real axis that represents the max ReZ
You know that the argument of Z is π/4
Cos π/4 = max ReZ/ √8 + 2
ReZ = 1/√2 * (√8+2)
ReZ= 2+ 2/√2