Find the Roots of a Quadratic Equation in C++

Quadratic Equation is nothing but a equation in terms of ax2+bx+c = 0 (where a, b and c are coefficients). The roots of the above equation is

Formula to find root of an quadratic equation

The term b2-4ac is referred as the discriminant of a quadratic equation. The discriminant tells the nature of the roots.

  • If discriminant is greater than 0, the roots are real and different.
  • If discriminant is equal to 0, the roots are real and equal.
  • If discriminant is less than 0, the roots are complex and different.
Find the Roots of a Quadratic Equation in C++
Find the Roots of a Quadratic Equation in C++

Find the Roots of a Quadratic Equation in C++

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

int main() {

    float a, b, c, x1, x2, discriminant, realPart, imaginaryPart;
    cout << "Enter coefficients a, b and 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 << "Roots are real and same." << endl;
        x1 = -b/(2*a);
        cout << "x1 = x2 =" << x1 << endl;
    }

    else {
        realPart = -b/(2*a);
        imaginaryPart =sqrt(-discriminant)/(2*a);
        cout << "Roots are complex and different."  << endl;
        cout << "x1 = " << realPart << "+" << imaginaryPart << "i" << endl;
        cout << "x2 = " << realPart << "-" << imaginaryPart << "i" << endl;
    }

    return 0;
}

If.. else condition iterates to find the roots of a quadratic equation. The real and imaginary parts are calculated using realPart = -b/(2*a); , imaginaryPart =sqrt(-discriminant)/(2*a); functions. If you enter the coefficients then the program displays the roots of the quadratic equation.

Read Also : Floyd's Triangle in C++

Output

Enter coefficients a, b and c: 4
5
1
Roots are real and different.
x1 = -0.25
x2 = -1

Final Words

I hope this article helps you to Find the Roots of a Quadratic Equation in C++ Program. If you face any issues please let me know via the comment section. Share this article with other C++ program developers via social networks.

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Hi, I'm Ranjith a full-time Blogger, YouTuber, Affiliate Marketer, & founder of Coding Diksha. Here, I post about programming to help developers.

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