Partial Fractions Calculator

This calculator performs partial fraction decomposition for the common case of a linear numerator divided by two distinct linear factors, splitting one fraction into a sum of two simpler ones. Partial fractions are a key technique in algebra and calculus, because a complicated rational expression is much easier to work with once it is broken into simple pieces. The method is essential for integrating rational functions, for inverse Laplace transforms in engineering, and for simplifying expressions in many areas of mathematics. The idea is to take a fraction of the form a linear expression over the product of two linear factors, and rewrite it as A over the first factor plus B over the second, where A and B are constants to be found. This tool handles that decomposition. You enter the numerator as a linear expression, giving its slope and constant, and the two distinct roots of the denominator factors. The calculator finds the constants A and B using the cover-up method, which evaluates cleverly chosen points to isolate each constant, and presents the full decomposition along with the individual values of A and B. The results update as you type, so you can explore how changing the numerator or the roots affects the breakdown. Use it to check calculus homework before integrating, to verify a decomposition by hand, or to learn the technique. The two roots must be different, since repeated or complex factors need a different form of decomposition that this tool does not cover. Once decomposed, each simple fraction integrates to a natural logarithm, which is exactly why this step is so useful in calculus.

2.667/(x - 1) + 0.333/(x + 2)
partial fraction decomposition
A2.667
B0.333
Roots1, -2

For (px + q) / ((x - a)(x - b)) with distinct roots a and b. Uses the cover-up method: A = (pa + q)/(a - b), B = (pb + q)/(b - a).

How it works

The expression (px + q) over (x - a)(x - b) is written as A over (x - a) plus B over (x - b). The cover-up method finds A by evaluating (px + q)/(x - b) at x = a, and B by evaluating (px + q)/(x - a) at x = b. This isolates each constant because the other term vanishes at that point.

Worked example

For (3x + 5) over (x - 1)(x + 2), the roots are 1 and -2. A is (3 times 1 plus 5) divided by (1 minus -2), which is 8 over 3, about 2.667. B is (3 times -2 plus 5) divided by (-2 minus 1), which is -1 over -3, about 0.333. So the decomposition is 2.667/(x - 1) + 0.333/(x + 2).

Related calculators

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland via SiteHost new Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.

© 2019 to 2026 Calculate.co.nz. All rights reserved.