【提问】谁知道这个代码问题是在哪？

# include <stdio.h>
# include <math.h>
int main (void)
{
int a = 1;
int b = 2;
int c = 1;
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解,x1 = %f, x2 = %f\n",x1,x2);
}
else if (delta = 0)
{
x1 = (-b)/(2*a);
x2 = x1;
printf ("该一元二次方程有一个唯一解,x1 = x2 = %f\n",x1);
}
else if (delta<0)
{
printf ("无解\n");
}
return 0 ;
}