What is complex conjugate of 4-2i?

Dec 3, 2015

$4 + 2 i$

Explanation:

As you can see, the complex conjugate, $\left(4 + 2 i\right)$, of your number is almost the same but with an opposite sign in the immaginary part.

An interesting property of complex conjugates is that if you multiply them together you get a pure real number!

So:

$\left(4 - 2 i\right) \left(4 + 2 i\right) = 16 \cancel{+ 8 i} \cancel{- 8 i} - 4 {i}^{2} = 16 - 4 {i}^{2} =$
but ${i}^{2} = - 1$
$= 16 \textcolor{red}{+} 4 = 20$ a pure real number!