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#include <fstream>
#include <cmath> 
using namespace std;
int main()
{
	double a,b,c,x1,x2;
	ifstream cin("input.txt");
	cin>>a>>b>>c;
	a!=0;
	(b*b-4*a*c)>=0;
	x1=(-1*b+sqrt(b*b - 4*a*c))/(2*a);
    cout<<"x1="<<x1;
    x2=(-1*b-sqrt(b*b-4*a*c))/(2*a);
    cout<<"x2="<<x2;
	ofstream cout("output.txt");
	cout<<fixed;
    cout.precision(3);
	cout<<x1<<x2;
	return 0;
}
 
 

prog.cpp: In function ‘int main()’:
prog.cpp:12:5: error: ‘cout’ was not declared in this scope
     cout<<"x1="<<x1;
     ^~~~
prog.cpp:12:5: note: ‘std::cout’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
prog.cpp:3:1:
+#include <iostream>
 using namespace std;
prog.cpp:12:5:
     cout<<"x1="<<x1;
     ^~~~

Standard output is empty