A small problem with complex conjugations

1. Jan 11, 2009

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!

2. Jan 11, 2009

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

3. Jan 11, 2009

Parnpuu

Yes I can see that now.

Thanks!