---
tag: 0XPKR18APA
kind: concept
name: Cofactor
msc: [15A15]
sources:
  - url: https://en.wikipedia.org/wiki/Minor_(linear_algebra)
    locator: First minors
---

## Summary

The cofactor in position $(i, j)$ of a square matrix is the first minor $M_{ij}$ with the sign $(-1)^{i+j}$.