when you multiply an complex number by its multiplicatuive identity, in case 4+8i, you would multiply both the top and the bottom by 4-8i which is actually the value one since we cannot actually change the whole value of the number. By multiplying it by 1 and we get the same value without the imaginary number
(sorry if this doesn't make sense but I hope it helps)
about that did you forget to put -4 + 8i just to make sure about it because I am not sure if you forget it or not just making sure
