For C programming!!!!

I need help getting my quadratic equation program to display the correct complex roots. when using a = -5, b = 3, c = -4, the answer displays as 0.3+-0.842615i and 0.3-0.842615i with that +- together and I do not understand how to fix it. I also need the code to run again if a user chooses. We have not even gone over this. I currently have the code in switch case. do I need to do something else?