c++入门，无可用源是什么情况？

[化拾again]

#include<iostream>
#include<iomanip>
#include<cmath>
using namespace std;
int main()
{
int a, b, c;
double x1, x2;
cin >> a >> b >> c;
if (b *b - 4 * a*c < 0)
{
cout << "s不存在" << endl;
}
else
{
x1 = (-b + sqrt(b *b - 4 * a*c)) / (2 * a);
x2 = (-b - sqrt(b *b - 4 * a*c)) / (2 * a);
}
cout << setiosflags(ios::fixed) << setiosflags(ios::right) << setprecision(2);
cout << x1 << endl;
cout << x2 << endl;
system("pause");
return 0;
}

[缘来是梦]

问题是跟代码有关的吗?

[赵4老师]

百度搜相关关键字。