Complex Number

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MAT067UniversityofCalifornia,DavisWinter2007
4+i
(d)
1
1+i
(e)(−i)
−1

2.Computetherealandimaginarypartsofthefollowingexpressions,wherezisthe
complexnumberx+yiandx,y∈R:

(a)
1

3z+2
(c)
z+1
2
(d)z3−4i=0

4.Calculatethe
(a)complexconjugateofthefraction(3+8i)4/(1+i)10.
(b)complexconjugateofthefraction(8−2i)10/(4+6i)5.
(c)complexmodulusofthefractioni(2+3i)(5−2i)/(−2−i).
(d)complexmodulusofthefraction(2−3i)2/(8+6i)2.

5.Computetherealandimaginaryparts:
(a)e
2+i
(b)sin(1+i)
(c)e
3−i
(d)cos(2+3i)

6.Computetherealandimaginarypartofeezforz∈C.
7.Leta∈Randz,w∈C.Provethat
(a)Re(az)=aRe(z)andIm(az)=aIm(z).
(b)Re(z+w)=Re(z)+Re(w)andIm(z+w)=Im(z)+Im(w).

8.Letz∈C.ProvethatIm(z)=0ifandonlyifRe(z)=z.
9.Letpbeapolynomialwithrealcoefficientsandz∈C.
Showthatp(z)=0ifandonlyp(
3
11.Letz,w∈Cwith
1−