#include <stdio.h>
#include <math.h>

int main(void)

{
int a,b,c;
float e ;
float  x1 , x2 ;


printf("a,b,c= ");
scanf ("a=%f,b=%f,c=%f\n",&a,&b,&c);
e = b * b - 4 * a * c;

       if (e > 0)
       {  
           x1 = (-b) + sqrt(e)/2 * a;
           x2 = (-b) - sqrt(e)/2 * a;
           printf("两个解 x1 = %f , x2 = %f\n", x1 , x2 );
       }
       else if (e == 0)
       {
           x1 = (-b)/2 * a;
           x2 = x1;
           printf("一个解 x1 = %f , x2 = %f\n", x1 , x2 );
       }
       else
       {
           printf("无解\n");
       }

return 0;
}

还是不合适，输出始终无解

就是输入abc三个只值，看此一元二次方程有几个解，分别等于多少