C++ Program for finding the roots of Quadratic Equation

Program to find the roots of Quadratic Equation

Here we will discuss how to find the roots of quadratic equation where it is given that real roots exists for  the given equation, using C++ programming language.

Quadratic Equation is equation of  the form ax2 + bx + c = 0, where a, b and c are real numbers and a != 0

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

  • If the discriminant is greater than 0, the roots are real and different.
  • If the discriminant is equal to 0, the roots are real and equal.
  • If the discriminant is less than 0, the roots are complex and different.
Quadratic Equations
Roots of Quadratic Equation

Algorithm:-

  1. Take coefficients of quadratic equation a,b,c  as  input from the user
  2. Calculate the discriminant  Discriminant = b2-4ac
  3. if Discriminant > 0 ,
        1. root1 = (-b + sqrt(Discriminant)) / (2 * a)
        2. root2 = (-b – sqrt(discriminant)) / (2 * a)
  4. if Discriminant == 0 ,
        1. root1 =-b / (2 * a)
        2. root2 = -b / (2 * a)
  5. if Discriminant < 0 ,
        1. root are imaginary

              realPart =  -b / (2 * a)

              imagPart = sqrt(-discriminant) / (2 * a)

        2. roo1 = realPart+imagPart i
        3. root2= realPart-imagPart i
  6. Print the roots

C++ Code:-

    
    //C++ Program
    //Program to find roots of quadratic equation
    #include<iostream>
    #include <math.h>
    using namespace std;

    int main() {
        double abcdiscriminantroot1root2realPartimagPart;
        cout<<“Enter coefficients a, b and c: “;
        cin>>a>>b>>c;

        discriminant = b * b – 4 * a * c;

        // condition for real and different roots
        if (discriminant > 0) {
            root1 = (-b + sqrt(discriminant)) / (2 * a);
            root2 = (-b – sqrt(discriminant)) / (2 * a);
            // to display the roots upto 2 decimal places 
            printf(“root1 = %.2lf and root2 = %.2lf”root1root2);
        }

        // condition for real and equal roots
        else if (discriminant == 0) {
            root1 = root2 = –b / (2 * a);
            printf(“root1 = root2 = %.2lf;”root1);
        }

        // if roots are not real
        else {
            realPart = –b / (2 * a);
            imagPart = sqrt(-discriminant) / (2 * a);
            printf(“root1 = %.2lf+%.2lfi and root2 = %.2f-%.2fi”realPartimagPartrealPartimagPart);
        }

        return 0;
    } 
    
    Output:-
    Enter coefficients a, b and c: 2.3
    4
    5.6
    root1 = –0.87+1.30i and root2 = –0.871.30i
coding (3)
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