c语言求一元方程的根

#include<stdio.h>

#include<math.h>

main()

{
float a,b,c,d;
float x1,x2;
printf("请输入三个系数:");
scanf("%f,%f,%f",&a,&b,&c);
d=b*b-4*a*c;
if(d==0)
printf("x1=x2=%.2f",-b/2*a);
else if(d>0)
printf("x1=%.2f,x2=%.2f",(-b+sqrt(d))/2*a,(-b-sqrt(d))/2*a);
else
{
x1=-b/2*a,x2=sqrt(-d)/2*a;
printf("x1=%.2fi+%.2fj\n",x1,x2);
printf("x2=%.2fi-%.2fj\n",x1,x2);
}

}