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

int main(void)
｛
 int a = 1;
 int b = 2;
 int c = 3;
 double delta;
 double x1;
 double x2;
 delta = b*b-4*a*C;

 if (delta > 0 )
 {
    x1 = (-b+sqrt(delta))/(2*a);
    x2 = (-b-sqrt(delta))/(2*a);
    printf("该一元二次方程有两个实数解，x1=%f,x2=%f\n",x1,x2,);
 }
  else if （delta == 0）
  {
      x1 = (-b)/(2*a);
      x1 = x2;
      printf("该一元二次方程有一个唯一解，x1=x2=%f\n",x1);
  }
  else
  {
    printf("该一元二次方程无解\n")；
  }
   

 return o;
｝

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

int main(void)
｛
 int a = 1;
 int b = 2;
 int c = 3;
 double delta;
 double x1;
 double x2;
 delta = b*b-4*a*C;

 if (delta > 0 )
 {
    x1 = (-b+sqrt(delta))/(2*a);
    x2 = (-b-sqrt(delta))/(2*a);
    printf("该一元二次方程有两个实数解，x1=%lf,x2=%lf\n",x1,x2,);
 }
  else if （delta == 0）
  {
      x1 = (-b)/(2*a);
      x1 = x2;
      printf("该一元二次方程有一个唯一解，x1=x2=%lf\n",x1);
  }
  else
  {
   printf("该一元二次方程无解\n")；
  }
   

   return o;//o
｝

还是不行

呵呵，