Quadratic equation in C

// Q equ //
#include <stdio.h>
#include <math.h>
void main()
{
  double a,b,c ;  // i use this for 0.000  real
  double m,n,r ;
  double real,imgn ;
  printf ("enter var A ") ;
  scanf ("%f", &a) ;
  printf ("enter var B ") ;
  scanf ("%f", &b) ;
  printf ("enter var C ") ;
  scanf ("%f", &c) ;
r = ( (b*b)-(4*a*c) ) ;  /* for specific        = 0  ,  >0   ,  <0 
                      two sismilar solution  ,  tow difrent solution ,  comlix root & number */

if (r>=0)
{
      m= ( (-b) + sqrt(pow(b,2) - (4*a*c)) ) / (2*a) ;
      n = ( (-b) - sqrt(pow(b,2) - (4*a*c)) ) / (2*a) ;


  printf ("X1 = %7.3f \n",m ) ;
  printf ("X2 = %7.3f \n",n ) ;

}
else
{
    printf ("complex root \n") ;
 

    real = (-b)/(2*a) ;
    imgn = sqrt(-r) /(2*a) ;
                                      // 7.3 refer to 000.000

    printf ("X1 = %7.3f + %7.3f i \n",real,imgn) ;
    printf ("X2 = %7.3f - %7.3f i \n",real,imgn) ;
}
}