Conjugate

[Zfuss12]

How would you show that the product of a+bi and its conjugate is a real number?

I did this:

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

but im not sure if this is right...or what eaxactly it proves and how

HELP PLEASE...!?

 

[Unco]

Almost! You've just forgotten to square the b!

 

[Zfuss12]

but how does that prove its a real number?

 

[Unco]

There is no imaginary component in your result, ie. there are no i's!