Python Program to Solve Quadratic Equation

In this article, we have provided a python source code that is capable of finding the roots for a quadratic equation if the user provides the program with coefficient values of x ² , x and constant.

Prerequisite topics to create this program

• Python Input, Output
• Python Data types
• Python Operators
• python modules

Steps

• ask the user to enter the coefficient values of a, b and c real numbers.
• calculate the discriminant value by suing the formula d = (b**2) - (4*a*c)
• At last, using the quadratic formula, we will calculate the two possible roots.
• A quadratic equation could have imaginary root values so for that here we will use the cmath module to perform the sqrt() function.

General Quadratic Equation

ax2 + bx + c = 0, where a, b and c are real numbers and a ? 0

Python Program to Solve Quadratic Equation Code

import cmath

a = float(input("Enter the coefficient of x sq: "))
b = float(input("Enter the coefficient of x: "))
c = float(input("Enter the constant of c sq: " ))

d = (b**2) - (4*a*c)    # calculate the discriminant

# find two root values
root_1 = (-b-cmath.sqrt(d))/(2*a)
root_2 = (-b+cmath.sqrt(d))/(2*a)

print('The two possible roots are {0} and {1}'.format(root_1,root_2))

Input

Enter the coefficient of x sq: 5
Enter the coefficient of x: 6
Enter the constant of c sq: 1

Output

The two possible roots are (-1+0j) and (-0.2+0j)

Behind the Code

Here the cmath.sqrt() method is used to find the square root of the discriminant value d. For some equation the d could be negative and when it happen the cmath.sqrt() function calculate the square root of the value in complex number.

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