How to simplify complex addition. I'm Bon Crowder with MathFour.com and we're talking about simplifying complex addition. Now complex addition means the addition of complex numbers which are numbers that have a real part and an imaginary part. So when I add these two complex numbers, I have to add the like terms so there's 3 + 2I + -8 + 7I. I don't need the parentheses any more, the 3 is the real part and so is the -8 so I can add those together to get -5. The 2I and the 7I are the imaginary parts and 7 and 2 make 9 so that's 9I. And so now we have -5 + 9I. Notice here we have the real part and here we have what's called the imaginary part. And that's how you simplify complex addition. I'm Bon Crowder with MathFour.com. Enjoy.