z1= 2(3+5i)-6i+3 = 6+10i-6i+3 = 3+4i
z2= 2i+3(1-6i) = 2i+3-18i = 3-16i
a)z1+z2= 3+4i+3-16i = 9-12i
b)z1-z2= 3+4i-(3-16i) = 3+4i-3+16i = 20i
c)z1xz2= (3+4i)(3-16i) = 9-48i+12i-64i² =
= 9-36i+64 = 73-36i
i²=-1→-64i²= -64 x (-1)=64
d)z1 supra z2 =
[tex] {}^{3 + 16i)} \frac{3 + 4i}{ 3- 16i} = \frac{9 + 12i + 48i + 64 {i}^{2} }{9 -256 {i}^{2} } = \\ = \frac{73 + 48i}{9 + 256} = \frac{73 + 48i}{265} [/tex]