C :

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

int main()
{
    double a,b,c,R1,R2;
	scanf("%lf %lf %lf", &a, &b, &c);
	if ((b*b-4*a*c) < 0 || a==0)
	{
	    printf("Impossivel calcular");
	}
	else
	{
		R1=(-b+sqrt(b*b-4*a*c))/(2*a);
		R2=(-b-sqrt(b*b-4*a*c))/(2*a);
	    printf("R1 = %.5lf\n",R1);
		printf("R2 = %.5lf\n",R2);
	}


    return 0;
}

C++ :

#include<bits/stdc++.h>


using namespace std;

int main()
{
    double a,b,c;
  
    scanf("%lf %lf %lf",&a,&b,&c);
    

    if(a==0||b*b-4*a*c<0) 
    printf("Impossivel calcular");

    else if(b*b-4*a*c>0)
    printf("R1 = %.5lf\nR2 = %.5lf\n",(-b+sqrt(b*b-4*a*c))/(2*a),(-b-sqrt(b*b-4*a*c))/(2*a));

    

    return 0;
}