Python Program to Solve Quadratic Equation

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This program computes the roots of a quadratic equation when coefficients a, b and c are known.

To understand this example, you should have the knowledge of following Python programming topics:

  1. WHAT IS PYTHON? THINGS TO KNOW BEFORE CODE WITH PYTHON
  2. HOW DO I GET AND INSTALL PYTHON?
  3. PYTHON PRIMITIVES – VARIABLES, BUILT-IN DATA TYPES, COMMENTS, SYNTAX, AND SEMANTICS
  4. CODING APPROACHES IN PYTHON
  5. STYLE GUIDE FOR PROGRAMMING PYTHON CODE
  6. ERRORS AND EXCEPTIONS IN PYTHON

The standard form of a quadratic equation is:

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

Source Code

# Solve the quadratic equation ax**2 + bx + c = 0

# import complex math module
import cmath

a = 1
b = 5
c = 6

# To take coefficient input from the users
# a = float(input('Enter a: '))
# b = float(input('Enter b: '))
# c = float(input('Enter c: '))

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

# find two solutions
sol1 = (-b-cmath.sqrt(d))/(2*a)
sol2 = (-b+cmath.sqrt(d))/(2*a)

print('The solution are {0} and {1}'.format(sol1,sol2))
Output

Enter a: 1
Enter b: 5
Enter c: 6
The solutions are (-3+0j) and (-2+0j)

We have imported the cmath module to perform the complex square root. First, we calculate the discriminant and then find the two solutions of the quadratic equation.

You can change the value of a, b and c in the above program and test this program.

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Pardeep Patel
Pardeep Patel

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Basics of Python