求方程有几个实数根

#include
int result_num(double a ,double b,double c)
{
if((b*b-4*a*c)/2*a>0)
{
return 2;
}
else if((b*b-4*a*c)/2*a==0)
{
return 1;
}
else 
{
return 0;
}


}


int main()
{
double a,b,c;
scanf("%f%f%f");
printf("方程的根%d个实数根\n",result_num(a,b,c));
}