# FOIL Method Calculator

> Expand two linear binomials using the FOIL method.

Page: https://askcalculators.com/calculator/foil-method-calculator/
Definition: https://askcalculators.com/calculator/foil-method-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/foil-method-calculator/schema.json
Version: 1.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/foil-method-calculator/?a=2&b=3&c=4&d=-5

## Inputs
- a: a in (ax + b); type=number; required; default=2
- b: b in (ax + b); type=number; required; default=3
- c: c in (cx + d); type=number; required; default=4
- d: d in (cx + d); type=number; required; default=-5

## Outputs
- expanded: Expanded polynomial; format=text; primary
- xSquaredCoefficient: x² coefficient; format=number
- xCoefficient: x coefficient; format=number
- constant: Constant; format=number
- steps: FOIL terms; format=text

## Formula
(ax + b)(cx + d) = acx² + (ad + bc)x + bd

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.