Partial Fraction Calculator

Decompose rational functions into partial fractions with step-by-step solutions

Enter Rational Function
Enter polynomials in standard form. Examples: x^2 + 3x + 2, (x+1)(x+2), x^2 - 4
Partial Fraction Decomposition
(x² + 3x + 2) / (x² + 2x + 1)
📋 Decomposed Form
1 + 1/(x+1) + 1/(x+1)²
📝 Step-by-Step Solution
1. Factor the denominator: (x+1)²
2. Set up partial fractions: A/(x+1) + B/(x+1)²
3. Multiply both sides by (x+1)²
4. Solve for A and B
5. Result: 1 + 1/(x+1) + 1/(x+1)²

Frequently Asked Questions

What is partial fraction decomposition?
Partial fraction decomposition is a method used to break down a rational function (a fraction with polynomials) into a sum of simpler fractions. It's commonly used in calculus to integrate rational functions, in algebra to solve equations, and in engineering for Laplace transforms.
When do I need to use partial fractions?
You typically need partial fractions when:
  • Integrating rational functions in calculus
  • Solving differential equations using Laplace transforms
  • Simplifying complex rational expressions
  • Finding inverse Laplace transforms
  • Analyzing control systems in engineering
What are the different cases for partial fractions?
There are four main cases:
  • Case 1: Distinct linear factors → A/(ax+b) + B/(cx+d)
  • Case 2: Repeated linear factors → A/(ax+b) + B/(ax+b)² + ...
  • Case 3: Distinct quadratic factors → (Ax+B)/(ax²+bx+c)
  • Case 4: Repeated quadratic factors → (Ax+B)/(ax²+bx+c) + (Cx+D)/(ax²+bx+c)²
How do I check if my partial fraction decomposition is correct?
To verify your decomposition, combine the partial fractions back into a single fraction by finding a common denominator. The result should equal the original rational function. Our calculator does this verification automatically and shows the steps.
What if the degree of numerator is greater than or equal to the denominator?
If the degree of the numerator is greater than or equal to the degree of the denominator (improper fraction), you must first perform polynomial long division to separate the quotient and remainder. Then you apply partial fraction decomposition to the remainder term. Our calculator handles this automatically.
How does partial fraction help with integration?
Partial fractions break complex rational functions into simpler terms that are easy to integrate. For example:
  • ∫ A/(x-a) dx = A ln|x-a| + C
  • ∫ A/(x-a)² dx = -A/(x-a) + C
  • ∫ (Ax+B)/(x²+px+q) dx involves arctan or natural log
This makes integration much more manageable.
What is the Heaviside cover-up method?
The Heaviside cover-up method is a shortcut for finding coefficients in partial fraction decomposition when factors are linear and distinct. You "cover up" one factor at a time in the original fraction and evaluate the remaining expression at the root of that factor to find its coefficient. It's much faster than solving systems of equations.

Partial Fraction Rules

  • Linear Factor (distinct): A/(ax+b)
  • Linear Factor (repeated): A₁/(ax+b) + A₂/(ax+b)²
  • Quadratic Factor (distinct): (Ax+B)/(ax²+bx+c)
  • Quadratic Factor (repeated): (A₁x+B₁)/(ax²+bx+c) + (A₂x+B₂)/(ax²+bx+c)²

Common Examples

  • 1/(x²-1) = 1/2(x-1) - 1/2(x+1)
  • 1/(x²+1) = No real linear factors
  • x/(x²-4) = 1/2(x-2) + 1/2(x+2)
  • 1/x(x+1) = 1/x - 1/(x+1)

Input Format Guide

  • x^2 + 3x + 2 → x² + 3x + 2
  • (x+1)(x+2) → (x+1)(x+2)
  • x^2 - 4 → x² - 4
  • x^3 - 1 → x³ - 1