Finding the roots of a Quadratic equation

#include<math.h>
int main() {
float a=2,b=4,c=1;
float d,root1,root2;
d= b*b-4*a*c;
if(d<0)
{
  printf("Roots are Complex\n");
  printf("The roots of Quadratic expession are");
  printf("%.3f%+.3fi",-b/(2*a),sqrt(-d)/(2*a));
    printf(", %.3f%+.3fi",-b/(2*a),-sqrt(-d)/(2*a));
 
    return 0;
  }
  else if(d==0){
   printf("Both roots are equal.\n");

   root1 = -b /(2* a);
   printf("Root of quadratic equation is: %.3f ",root1);

   return 0;
  }
  else{
   printf("Roots are real numbers.\n");
 
   root1 = ( -b + sqrt(d)) / (2* a);
   root2 = ( -b - sqrt(d)) / (2* a);
   printf("Roots of quadratic equation are: %.3f , %.3f",root1,root2);
  }

  return 0;
}