Free Math Calculator

Partial Fraction Integration Calculator

Integrate rational functions step by step using polynomial division, denominator factorization, partial fractions, verification and integration.

Calculate a Partial Fraction Integral

Enter the numerator \(P(x)\) and denominator \(Q(x)\) of a rational function \(\frac{P(x)}{Q(x)}\). The calculator will show the algebraic steps.

Example: 2x+3
Example: (x+1)(x+2)
Try an example:

What Is Partial Fraction Integration?

Partial fraction integration is a method for integrating rational functions. A rational function is a quotient of two polynomials:

\[ \frac{P(x)}{Q(x)} \]

When the denominator can be factored, the fraction can often be rewritten as a sum of simpler fractions. These simpler expressions are then easier to integrate.

For example:

\[ \frac{2x+3}{(x+1)(x+2)} = \frac{1}{x+1} + \frac{1}{x+2} \]

Each resulting term can then be integrated using familiar formulas such as the logarithm rule.

How the Calculator Works

1. Check the rational function

The numerator and denominator are interpreted as polynomials in \(x\).

2. Polynomial long division

If the numerator has degree greater than or equal to the denominator, polynomial division is performed before partial fractions.

3. Factor the denominator

The calculator looks for linear factors and supported quadratic factors.

4. Find partial-fraction coefficients

A coefficient system is constructed and solved algebraically.

5. Verify the decomposition

The calculator recombines the partial fractions and compares the resulting polynomial with the original numerator.

6. Integrate the simpler terms

Linear factors produce logarithmic or power integrals, while supported quadratic factors use the corresponding quadratic integration formulas.

Common Partial Fraction Forms

The form of the decomposition depends on how the denominator factors.

Distinct linear factors

\[ \frac{P(x)} {(x-a)(x-b)} = \frac{A}{x-a} + \frac{B}{x-b} \]

Repeated linear factors

\[ \frac{P(x)} {(x-a)^2} = \frac{A}{x-a} + \frac{B}{(x-a)^2} \]

More generally, a repeated factor requires one partial-fraction term for each power of that factor.

Irreducible quadratic factors

\[ \frac{P(x)} {x^2+bx+c} = \frac{Ax+B} {x^2+bx+c} \]

The numerator over an irreducible quadratic is linear because its degree must be smaller than the degree of the quadratic denominator.

Partial Fraction Integration Examples

Example 1: Two linear factors

\[ \frac{2x+3} {(x+1)(x+2)} \]

The denominator has two distinct linear factors, so the fraction can be separated into two simple logarithmic terms.

Example 2: Repeated factor

\[ \frac{3x+5} {(x-1)(x+1)^2} \]

The repeated factor \((x+1)^2\) requires terms involving both \(x+1\) and \((x+1)^2\).

Example 3: Linear and quadratic factors

\[ \frac{x+2} {(x-1)(x^2+1)} \]

The quadratic \(x^2+1\) is irreducible over the real numbers and uses a linear numerator in its partial-fraction term.

Example 4: Improper rational function

\[ \frac{2x^2+3x+1} {x^2+1} \]

Because the numerator and denominator have the same degree, polynomial long division is performed first.

Why Polynomial Long Division Comes First

Partial fractions are normally applied to a proper rational function, where \(\deg P < \deg Q\).

If \(\deg P \geq \deg Q\), polynomial long division separates the expression into a polynomial plus a proper rational fraction.

\[ \frac{P(x)}{Q(x)} = S(x) + \frac{R(x)}{Q(x)} \] \[ \deg R < \deg Q \]

The polynomial \(S(x)\) can be integrated directly, while the proper fraction \(R(x)/Q(x)\) can then be decomposed using partial fractions.

Supported Input

Note: The calculator is designed for rational functions whose denominator can be factored into supported linear and quadratic polynomial factors. It does not attempt to factor every possible high-degree polynomial.

Partial Fractions vs. Other Integration Methods

Partial fractions are especially useful when the integrand is a quotient of polynomials.

Other functions may be better handled with different methods:

Frequently Asked Questions

What is partial fraction integration?

Partial fraction integration rewrites a rational function as a sum of simpler rational expressions. Each simpler expression can then be integrated using standard formulas.

When should I use partial fractions?

Partial fractions are commonly used when integrating a rational function, meaning a quotient of two polynomials. Factoring the denominator determines the form of the decomposition.

What if the numerator has a larger degree?

The calculator performs polynomial long division first. This separates the expression into a polynomial and a proper rational fraction.

Does the calculator show the steps?

Yes. The solution can show polynomial division, denominator factorization, partial-fraction decomposition, algebraic verification and integration.

Does it support repeated linear factors?

Yes. For example, denominators containing \((x+1)^2\) can be decomposed into terms involving \(x+1\) and \((x+1)^2\).

Does it support quadratic factors?

Yes. Supported irreducible quadratic factors use a linear numerator in the partial-fraction decomposition. Some repeated-root quadratic cases require additional simplification and may not be fully evaluated by this version of the calculator.

© 2026 Summe.org