Question

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

Answer 1

(a+bi)(a-bi) = a^2 + b^2

Answer 2

let z = 1 + 2i
therefore it conjugate is given as
conjugate z= 1-2i
z*conjugate z = (1+2i)(1-2i) = 1^2 - (2i)^2 = 1- 4i^2= 1-4(-1) =1+4 = 5 ( since i^2 =-1)

Answer 3

et z = 1 + 2i
therefore it conjugate is given as
conjugate z= 1-2i
\[z*conjugate z = (1+2i)(1-2i) = 1^2 - (2i)^2 = 1- 4i^2= 1-4(-1) =1+4 = 5\] ( since \[i^2 =-1\])