将第七题写一个程序来解答

代码如下：

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
    double a,b,c;
    double q = b*b - 4*a*c;
    double x1,x2;
    cin >> a>>b>>c;
    if(a == 0)
    {
        x1 = -c/b;
        cout << x1;
        return 0;
    }
    if(q > 0)
    {
        x1 = (-b + sqrt(q))/(2*a);
        x2 = (-b - sqrt(q))/(2*a);
        cout << "方程有2个实根：x1=" << x1 <<",x2="<<x2<<endl;
    }else if(q==0)
    {
        x1 = (-b)/(2*a);
        cout << "方程有一个实根："<<x1<<endl;
    }else
    {
        x1 = (-b)/(2*a);
        x2 = sqrt(-q)/(2*a);
        cout << "方程有两个虚根：x1 = " << x1 << "+" << x2 <<"i,x2=" << x1 << "-"<<x2<<"i"<<endl;
    }
    return 0;
}