题目链接

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

signed main(){
    double a, b, c;
    cin >> a >> b >> c;
    double delta = b*b - 4*a*c;
    if (delta < 0 || a == 0){
        cout << "Impossivel calcular";
        return 0;
    }
    double r1 = (-b+sqrt(delta)) / (2*a); //这两行记得加括号，不然运算顺序不对！
    double r2 = (-b-sqrt(delta)) / (2*a);
    printf("R1 = %.5lf\nR2 = %.5lf", r1, r2);
    return 0;
}