C++ Program to Find Roots of Quadratic Equation

This c++ program calculates the roots of quadratic equation. A quadratic equation is (ax^2 + bx + c =0), where a, b and c are coefficients. 

Roots are calculated as (-b ± sqrt(b*b - 4*a*c)) / (2*a)

Where, (b*b - 4*a*c) is known as determinant of quadratic equation.

If determinant > 0, then roots are

Root1 = (-b + sqrt(b*b - 4*a*c)) / (2*a)

Root2 = (-b - sqrt(b*b - 4*a*c)) / (2*a)

If determinant = 0, then roots are

Root1 = Root2 = -b/(2*a)

If determinant < 0, then roots are

Root1 = -b/(2*a) + i(sqrt(-d)/(2*a))

Root2 = -b/(2*a) - i(sqrt(-d)/(2*a))

C++ Program to Find Roots of Quadratic Equation

#include<iostream>

#include<cmath>

using namespace std;

int main()

{

    float a, b, c, d;

    float root1, root2, img, real;

    cout<<"Enter the coefficients of quadratic equation (ax^2+bx+c=0)\n";

    cin>>a>>b>>c;

    d = b*b - 4*a*c;

    if(d>0)

    {

        root1=(-b+sqrt(d))/(2*a);

        root2=(-b-sqrt(d))/(2*a);

        cout<<"\nRoots are real and distinct";

        cout<<"\nRoots are "<<root1<<" and "<<root2;

    }

    else if(d==0)

        {

            root1=root2=-b/(2*a);

            cout<<"\nRoots are real and equal";

            cout<<"\nRoots are "<<root1<<" and "<<root2;

        }

        else{

            real = -b/(2*a);

            img = sqrt(-d)/(2*a);

            cout<<"\nRoots are complex and imaginary";

            cout<<"\nRoots are "<<real<<"+"<<img<<"i and "<<real<<"-"<<img<<"i";

        }

    return 0;

}

OUTPUT:

Enter the coefficients of quadratic equation (ax^2+bx+c=0)

1

5

2

Roots are real and distinct

Roots are -0.438447 and -4.56155