C++ 实例 _ 求一元二次方程的根

C++ 实例 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

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