Simple c program for find roots of polynomial (basic coding).

This program is for find roots of polynomial in which X has maximum power is 2 and coefficient of X^2 is not equal to zero.
#include<stdio.h>
#include<math.h>

void main()
{
     float a,b,c,d,e,f;
     printf("enter the  coefficient of X^2:");
     scanf("%f",&a);
     printf("enter the  coefficient of X:");
     scanf("%f",&b);
     printf("enter the value of  constant:");
     scanf("%f",&c);
     d=(b*b)-(4*a*c);
     if(d>=0&&a!=0)
        {
                 e=(-b+sqrt(d))/(2*a);
                 f=(-b-sqrt(d))/(2*a);
            printf ("Root 1 =%f",e);
            printf ("Root 2 =%f",f);
         }
      if(d<0&&a!=0)
         {
           e=-b/(2*a);
            f=sqrt(-d)/(2*a);
           printf ("Root 1=%f+%fi",e,f);
           printf ("Root 1=%f-%fi",e,f);
          }

}

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