Question

Find the product of the complex number and its conjugate.
1 + 2i

Select one:
a. 1 - 4i
b. -3
c. 5
d. 1 + 4i

Answer 1

the congugat of a+bi is a-bi.
so the congugate of 1+2i is 1-2i.
(1+2i)*(1-2i)=1*1-2i+2i-(2i*2i)=1-(2*-1)=1+2=3

Answer 2

woops:
(1+2i)*(1-2i)=1-2i+2i+4=1+4=5

Answer 3

sorry made a mistake

Answer 4

Thank you!

Answer 5

np :)

Answer 6

:D :P
you are welcome