题解 | #计算一元二次方程#

#include<bits/stdc++.h>
using namespace std;
int main()
{
//     (-b±√(b^2-4ac))/2a
    float a,b,c;
    while(cin>>a>>b>>c)
    {
        float delta = pow(b,2)-4*a*c;
        if(!a)
            cout<<"Not quadratic equation"<<endl;
        else
        {
            if(!delta)
                cout<<fixed<<setprecision(2)<<"x1=x2="<<((-1)*b)/(2*a)+delta<<endl;
            else if(delta>0)
                cout<<fixed<<setprecision(2)<<"x1="<<(sqrt(delta)+b)/((-2)*a)<<";x2="<<(sqrt(delta)-b)/(2*a)<<endl;
            else
            {
                cout<<fixed<<setprecision(2)<<"x1="<<(-b)/(2*a)<<"-"<<abs(sqrt((-1)*delta)/(2*a))<<"i";
                cout<<fixed<<setprecision(2)<<";x2="<<(-b)/(2*a)<<"+"<<abs(sqrt((-1)*delta)/(2*a))<<"i"<<endl;
            }
        }
    }
    return 0;
}