A small problem with complex conjugations

[Parnpuu]

Hi!

I have a problem with understanding an equation which is really simple.

zz*=(a²+b²)

shouldn't there be an i there if

z₁z₂=(a₁+ib₁)(a₂+ib₂)

is the equation correct?

If it is could someone explain to me why there is no imaginary number?

Thank You!

 

[snipez90]

if z = a + bi, then z* (conjugate of z) = a - bi so

(z)(z*) = (a+bi)(a-bi) = a² - (bi)² = a² -(i)²b² = a² -(-1)b² = a² + b²

 

[Parnpuu]

Yes I can see that now.

Thanks!