求解一元二次方程

#include <math.h>
#include <stdio.h>
#pragma warning (disable:4996)
#define EXP 0.0000001
int main()
{
double a=0.0;
double b=0.0;
double c=0.0;
scanf("%lf%lf%lf", &a,&b,&c);

if((a>-EXP)&&(a<EXP))
{
printf("是一元一次方程\n");
}
else
{
double disc = b*b-4*a*c;
if((disc<EXP)&&(disc>-EXP))
{
double x = -b/(2*a);
printf("%f\n", x);
}
else if(disc>0.0)
{
double x1 = (-b+sqrt(disc))/(2*a);
double x2 = (-b-sqrt(disc))/(2*a);
printf("x1 = %f x2 = %f\n", x1,x2);
}
else
{
printf("有两个共轭的复根\n");
}
}
system("pause");
return 0;
}