【练习题1】求方程ax2+bx+c=0的根，请编码实现

思路：
用if判断b的平方-4ac的三种情况，从而来决定有几个根，如何输出根。

#include<iostream> //#include<math> using namespace std; int main() {int a, b, c,x,y,x1,x2;cin >> a;cin >> b;cin >> c;if (b*b - 4*a*c < 0){printf("have not sqrt");}if (b*b - 4 * a*c == 0){x = -b / (2*a);cout <<"sqrt:"<< x << endl;}if (b*b - 4 * a*c > 0){y = sqrt(b * b - 4 * a*c);x1 = (-b + y) / (2*a);x2 = (-b - y) / (2 * a);cout <<"sqrt one:"<< x1 << endl;cout <<"sqrt two:" <<x2 << endl;} }