C++ 实例 – 求一元二次方程的根

最后更新于：2022-03-27 02:33:57

C++ 实例 – 求一元二次方程的根

C++ 实例 – 求一元二次方程的根 C++ 实例

二次方程 ax2+bx+c = 0 (其中a≠0），a 是二次项系数，bx 叫作一次项，b是一次项系数；c叫作常数项。

x 的值为：

根的判别式

实例

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

int main() {

float a, b, c, x1, x2, discriminant, realPart, imaginaryPart;
cout << "输入 a, b 和 c: ";
cin >> a >> b >> c;
discriminant = b*b – 4*a*c;

if (discriminant > 0) {
x1 = (–b + sqrt(discriminant)) / (2*a);
x2 = (–b – sqrt(discriminant)) / (2*a);
cout << "Roots are real and different." << endl;
cout << "x1 = " << x1 << endl;
cout << "x2 = " << x2 << endl;
}

else if (discriminant == 0) {
cout << "实根相同：" << endl;
x1 = (–b + sqrt(discriminant)) / (2*a);
cout << "x1 = x2 =" << x1 << endl;
}

else {
realPart = –b/(2*a);
imaginaryPart =sqrt(–discriminant)/(2*a);
cout << "实根不同：" << endl;
cout << "x1 = " << realPart << "+" << imaginaryPart << "i" << endl;
cout << "x2 = " << realPart << "–" << imaginaryPart << "i" << endl;
}

return 0;
}

以上程序执行输出结果为：

输入 a, b 和 c: 4
5
1
实根不同：
x1 = -0.25
x2 = -1

C++ 实例 – 求一元二次方程的根 C++ 实例